Skip to main content

Full text of "soil analysis"

See other formats


GRADES 10-12 

written by 

Jeanmarie Kennedy 

Armijo High School 

Fairfield Suisun Unified School District 

Fairfield, CA 

for the 

California Foundation for Agriculture in the Classroom 

in cooperation with the 

California Department of Education 

California Department of Food and Agriculture 

California Farm Bureau Federation 

Fertilizer Inspection Advisory Board 

Fertilizer Research and Education Program 


M argaret A nderson 
Pamela Emery 
Carolyn McClelland 

California Foundation For 

Agriculture I n TheClassroom 

1601 Exposition Boulevard 

Sacramento, CA 95815 

(916) 924-4380 

September, 1994 


Acknowledgments 2 

Introduction ' * *.* 5 

Getting Started 

Unit Overview 6 

Time Requirements 8 

Materials List 9 


Chemically Speaking - What's in a Plant? 10 

A Chemical View of the World! 14 

How to Determine the Percent of Available Nutrients in Fertilizers 26 

Making a Fertilizer and Testing for Phosphates 36 

A Letter to Your Grandfather! 45 

Teacher Resources 

Selected Student Reading Assignments 48 

Background and Educational Resources 62 

Useful Organizations and Companies 66 

Glossary 69 

Footnotes 7 1 


This unit was funded by a grant from the Fertilizer Research and Education Program, the 
California Foundation for Agriculture in the Classroom, the California Department of Food and 
Agriculture, the Fertilizer Inspection Advisory Board and the California Farm Bureau 

The Fertilizer Research and Education Program provides funding to conduct research and 
education projects directed toward the environmentally safe and agronomically sound use and 
handling of fertilizer materials. 

The California Foundation for Agriculture in the Classroom is dedicated to fostering a greater 
public knowledge of the agricultural industry and seeks to enlighten students, educators, and 
leaders in the public and private sector about agriculture's vital, yet sometimes forgotten, role 
in American society and the effect all citizens have on agriculture's well being. 

We would like to thank the following people who helped create, write, revise and edit this unit. 
Their comments and recommendations contributed significantly to the development of this unit. 
However, their participation does not necessarily imply endorsement of all statements in the 



Pilot Testers 

Jean Kennedy 
Agriculture Teacher 
Armijo High School 
Fairfield-Suisun Unified School 
Fairfield, CA 

Margaret Anderson 
Communications Consultant 
Birds Landing, CA 

Pamela Emery 
Curriculum Coordinator 
California Foundation for 
Agriculture in the Classroom 
Sacramento, CA 

Carolyn McClelland 
English Teacher 
Dover Middle School 
Fairfield-Suisun Unified School 
Fairfield, CA 

Jean Kennedy 
Agriculture Teacher 
Armijo High School 
Fairfield-Suisun Unified School 
Fairfield, CA 

Dennis Shiermeyer 
Chemistry Teacher 
Woodland High School 
Woodland Joint Unified School 
Woodland, CA 

Scott Zgraygen 

Physical Science/Chemistry 


Vacaville High School 

Vacaville Unified School District 

Vacaville, CA 

Curriculum Advisory 
and Review Committee 

Lois Andre Bechely 
Teacher/Educational Consultant 
Los Angeles, CA 

Clark Biggs 
Information Director 
California Farm Bureau 
Sacramento, CA 

Joanne Borovoy 

Kindergarten Teacher 

John B. Reibli School 

Mark West Union School District 

Santa Rosa, CA 

Francine Bradley, Ph.D. 
Cooperative Extension Avian 
Sciences Specialist 
University of California 
Davis, CA 

Beth Brookhart 
Freelance Journalist 
Bakersfield, CA 

Barbara Buck 
Executive Vice President 
Fresh Produce and Floral Council 
Los Angeles, CA 

Lucas Calpouzos, Ph.D. 
Former Dean of Agriculture 
California State University 
Chico, CA 

Debbie Calvo 
Executive Director 
Alliance for Food and Fiber 
Los Angeles, CA 

Jerry Delsol 
Agriscience Teacher 
Douglass Junior High School 
Woodland Joint Unified School 
Woodland, CA 

Pamela Emery 
Curriculum Coordinator 
California Foundation for 
Agriculture in the Classroom 
Sacramento, CA 

Richard Engel 
Agriscience Teacher 
Woodland Senior High School 
Woodland Joint Unified School 
Woodland, CA 

Jacques Franco 
Program Coordinator 
California Department of Food 
and Agriculture 
Fertilizer Research and 
Education Program 
Sacramento, CA 

David Hammond 

Lead Consultant 

California Department of 


Science and Environmental 

Science Unit 

Sacramento, CA 

Carolyn Hayworth 
Manager, Investor and Public 
Calgene, Inc. 
Davis, CA 

Karen Holtman 

Kindergarten Teacher 

John B. Reibli School 

Mark West Union School District 

Santa Rosa, CA 

Wendy Jenks 
Director of Programs 
California Fertilizer Association 
Sacramento, CA 

Jean Kennedy 
Agriscience Teacher 
Armijo High School 
Fairfield-Suisun Unified School 
Fairfield, CA 

Kelly King 
Teacher Specialist 
Glenoaks Elementary School 
Glendale Unified School District 
Glendale, CA 

Carrie LaLonde 
Operations Manager 
Valley Fruit and Produce Council 
Los Angeles, CA 

Jean Landeen 

Agricultural Education 


California Department of 


Agricultural Education 

Sacramento, CA 

Mark Linder 


California Foundation for 

Agriculture in the Classroom 

Sacramento, CA 

Cynthia Livingston 
ESL Teacher Specialist 
Marshall Elementary School 
Glendale Unified School District 
Glendale, CA 

Al Ludwick 

Western Director 

Potash and Phosphate Institute 

Mill Valley, CA 

Holiday Matchett 
Elementary Science Teacher 
Dingle Elementary School 
Woodland Joint Unified School 
Woodland, CA 

Craig McNamara 


Sierra Orchards 

Winters, CA 

Donna Mitten 
Director, Product Planning 
Calgene, Inc. 
Davis, CA 

Robyn Moore 
Elementary School Teacher 
Presentation Elementary School 
Sacramento County 
Sacramento, CA 

Michael Moores 

Biology Teacher 

Yuba City High School 

Yuba City Unified School District 

Yuba City, CA 

Pam Mossman 

Fourth Grade Teacher 
Sandrini Elementary School 
Panama-Buena Vista Union 
School District 
Bakersfield, CA 

Robert Padgett 
Senior Account Executive 
The Dolphin Group 
Sacramento, CA 

Wendell Potter, Ph.D. 
Vice Chairperson 
Physics Department 
University of California 
Davis, CA 

Wynette Sills 


Pleasant Grove Farm 

Pleasant Grove, CA 

Roger Sitkin 


Old Dog Ranch 

Linden, CA 

Michael Sixtus 

Chemistry Teacher 

Mar Vista Senior High School 

Sweetwater Union High School 


Imperial Beach, CA 

Albert Squatrito 
Chemistry/Physics Teacher 
Granada Hills High School 
Los Angeles Unified School 
Granada Hills, CA 

Nancy Stevens 

Biology Teacher 

San Rafael High School 

San Rafael City High School 


Santa Rafael, CA 

Michael Toscano 

High School Agriculture Teacher 

Las Plumas High School 

Oroville Union High School 


Oroville, CA 

Laura Tower 

Project Coordinator 
California Foundation for 
Agriculture in the Classroom 
Sacramento, CA 

KarenBeth Traiger 
Elementary Science Teacher 
Graystone Elementary School 
San Jose Unified School District 
San Jose, CA 

Denise Van Horn 
Fourth Grade Teacher 
McSwain Elementary School 
McSwain Union Elementary 
School District 
Atwater, CA 

John Vogt 

Science Teacher 
Dover Middle School 
Fairfield-Suisun Unified School 
Fairfield, CA 

Gil Walker 

Elementary Science Teacher 
Gibson Elementary School 
Woodland Joint Unified School 
Woodland, CA 

Casey Walsh-Cady 

Research Assistant 

California Department of Food 

and Agriculture 

Fertilizer Research and 



Sacramento, CA 

Mary Yale 

Science Teacher 
Grange Middle School 
Fairfield-Suisun Unified School 
Fairfield, CA 


Jack Armstrong 
Karin Bakotich 
Sherri Freeman 

Lavout. Tvpina and 

Karin Bakotich 

Sherri Freeman 

Tami Gutschall 

Lyn Hyatt 


The Science Framework for California Public Schools e mphasizes the need to make science 
education more meaningful to students so they can apply what they learn in the classroom to 
their daily lives. Since all students eat food and wear clothing, one natural connection between 
science and the real world is agriculture. 

Agriculture is an enormous industry in the United States, especially in California. As more 
rural areas become urbanized and more challenges exist to maintain and improve the quality of 
the planet and feed the people of the world, it is extremely important to educate students about 
their environment and about agriculture. 

Agriculture, today, is very dependent on general and analytical chemistry concepts. The nature 
of fertilizers and their interactions with soil, water and air greatly influence how and when 
fertilizers are used. Challenges facing agriculture are clearly illustrated in this unit as 
students make a fertilizer, analyze fertilizers for phosphate content and discuss fertilizer 
labeling. The lessons in this unit are structured to encourage students and teachers to 
"construct" their own knowledge about agriculture and the environment and provide enough 
background information to make the teacher feel confident in the subject matter. 

The California Foundation for Agriculture in the Classroom is dedicated to fostering a greater 
public knowledge of the agricultural industry and seeks to enlighten students, educators, and 
leaders in the public and private sector about agriculture's vital, yet sometimes forgotten, role 
in American society and the effect all citizens have on agriculture's well being. Please contact 
the Foundation for assistance on the integration of agriculture into existing curriculum. Your 
comments on this unit or on other Agriculture in the Classroom resources are always welcome. 



This unit, intended for use in high school chemistry classes, uses fertilizer science as a tool to 
apply chemistry concepts to real world situations. Life and earth science concepts are applied 
throughout the unit making the lessons appropriate for integrated science classes. Through a 
series of hands-on labs and activities, practice problems, discussions and writing assignments, 
students learn about fertilizer chemistry as they break compounds into ions, make a fertilizer 
and test various fertilizers for phosphate content. What nutrients are required by plants, how 
these nutrients are obtained and the issues related to fertilizers and the environment are 


. Systems and Interactions 

• Stability 

• Energy 

. Scale and Structure 


(Footnotes refer to specific pages in the 1990 California Science Framework for Public 
Schools. ) 

Plants, as all matter, are made of chemical elements. 1 

Soil and water are amended with nutrients so plants get the nutrients they require. 

It appears that plants require 17 essential chemical elements as nutrients which can only be 
absorbed in certain forms through root uptake or leaf absorption. 2 

A fertilizer is any natural or manufactured material added to soil or water in order to 
supply one or more essential chemical nutrients to plants. 3 

Fertilizers come in a variety of forms and mixtures of different chemical ions. 

Fertilizers are made in a variety of ways. 4 

Fertilizers are made of elements and can be tested to measure the amounts of those elements. 

Fertilizers do not all contain the same percentages of each of the primary nutrients; 
fertilizers are prepared in different compositions so the consumer, farmer or home 
gardener, can apply only what is needed to the soil? 

The concepts relating to plant nutrient uptake are complex. 2 

Though fertilizers are an important part of crop production, over-fertilization and misuse 
can be harmful to the environment. In order to be effective, fertilizers must be used 

Chemistry learned in the classroom is applicable to the real world and affects the lives of all 
people, including farmers and consumers.6 

There are many career opportunities related to agriculture that do not directly involve 
production agriculture. 


These activities can be used in a variety of sequences. Skim over the entire unit before 
beginning it with your students. Pick the sequence that will work best with your curriculum. A 
suggested sequence is described below. 

1 . Chemically Speaking - What's in a Plant? 

2. A Chemical View of the World! 

3. How to Determine the Percent of Available Nutrients in Fertilizers 

4. Making a Fertilizer and Testing for Phosphates 

5. A Letter to Your Grandfather! 


Several assessment tools are built into this unit. Evaluate each student's active participation in 
lab activities as well as in discussions. "A Letter to Your Grandfather" can be used as an 
evaluation tool. The changes that occur in the student's review of the "Chemically Speaking! - 
What's In A Plant?" assignment also can be included in student portfolios. 


General Time Frame 

This unit is designed to cover a two week time span. Make sure you allow enough time for lab 
preparation and set-up. Honors and Advanced Placement classes may require less than two 

Chemically Speaking! - What's in a Plant? 

1 twenty-minute session 

1 ten-minute session at conclusion of unit 

A Chemical View of the World! 

1-2 forty-minute session(s) to complete poster 
1 forty-minute session for presentations 

1 forty-minute session to complete "Chemical Formulas and Available Ions in a 

How to Determine the Percent of Available Nutrients in Fertilizers 

1 forty-minute session 

Making a Fertilizer and Testina for Phosphates 

2 hours of teacher preparation 
2-3 forty-minute lab sessions 

A Letter to Your Grandfather! 

1 ten-minute session for introduction 

3-4 nights to complete writing assignment 

1 twenty-minute session for conclusion 

Allow 1 week for students to research topic as homework. 


Specific quantities of materials are listed at the beginning of each individual lesson. The 
following list provides you with an overview of what materials are necessary to complete the 
entire unit. 


Bunsen burners 

Ammonium molybdate (NH^MoCX} 

Ascorbic acid 

Concentrated sulfuric acid 

K2HPO4 (potassium phosphate) 



Colored pencils or markers 
Commercial fertilizer 
Construction paper or butcher paper 
Distilled water 
Filter paper 

Graduated cylinders 
Handouts-supplied in this unit 
Periodic Tables 
Plant-any type 

Reference books-see Teacher Resource section 
Ring clamps 
Ring stands 
Scotch tape 
Stirring rods 
Test tubes 
Test tube labels 
Wire gauze 



The purpose of this activity is for students to relate the chemical elements they learn about in 
the classroom to the world of plants and production agriculture. Students will focus on the 
general chemical composition of plants and discover where the required elements come from. 
This focus activity assists the instructor in finding out what conceptions students have about the 
chemistry of plants, fertilizers and the environment and encourages the students to think about 
the topics before they learn more about them. 


• Plants, as is all matter, are made of chemical elements. 1 

Soil and water are amended with essential elements so plants get the nutrients they require. 

• Photographs of corn fields and forests (optional) 
. One plant 

Copies of "Chemically Speaking - What's in a Plant?" handout (1 for each student) 
Various articles related to plant nutrient requirements and current issues associated with 
plant nutrient requirements (see Teacher Resource section) 

• Periodic Table of the Elements 


1 twenty-minute session 

1 ten-minute session at the conclusion of the unit 


This introductory lesson allows the students to think about what they already know about 
chemical elements that make up plants. Encourage your students to think for themselves and 
relate their thinking to their own experiences. This will make the unit more meaningful to each 
individual. After reading your students' responses to the questions, tailor your upcoming 
lessons to clarify misconceptions on the subject matter. 

Research has shown that plants require 17 chemical elements, and they are required in certain 
forms. These elements will be discussed in more detail in upcoming lessons. Recently, at the 
University of California at Davis, the 17th essential element was identified as nickel. Perhaps 
other essential elements will be identified in the future. Information on nickel is not present in 
most books/references due to its recent discovery as an essential plant nutrient. 


1 . Show students a plant. 

2. Ask the students to think of this plant in detail. What are the building blocks of this plant? 

What has to happen to keep this plant alive? 

3. Explain the purpose of this focus activity to your students. (See Purpose and Background 

Information) If available, show the students photographs of corn fields and forests. 


4. Have students complete the worksheet "Chemically Speaking - What's In A Plant?" Spend as 
much time on this lesson as you deem appropriate. Critical thinking and conceptualizing 
take more time for some students than for others. 

5. Have students read several articles about plant nutrient requirements, fertilizers, etc. 
Have them complete question #7 of their worksheet. Choose articles from the Teacher 
Resources section of this unit or use articles you have acquired. 

6. Discuss the students' answers to the questions. Perhaps you may choose to post different 
answers so that students can see them as they complete the unit. Save your students' 
worksheets for the end of the unit. 

7. Complete the rest of this unit as indicated. Refer to this lesson when appropriate. 

8. At the conclusion of this unit, return the questionnaires to the students. Have them look at 
their answers and prepare a written or oral explanation of how their conceptions of plant 
chemistry have been confirmed or have changed. 


Plants require essential elements for proper growth and reproduction. Fertilizers can 
provide plants with these necessary elements. 


Have students pretend they are a molecule that becomes absorbed into a plant. Have them 
discuss their journey in the plant and how they eventually are recycled back into the 


Have students make up a lesson which explains, to a kindergarten class, how plants get 
nutrients from the soil. Arrange for selected students to teach their units to kindergartners. 

1 1 

Student Handout Name 


imagine walking through a forest or a field of corn stalks that stand taller than your head. 
Biologically speaking, it is relatively easy to visualize the life cycle of these plants ... seeds 
are planted, they sprout, continue to grow and then, at maturity, produce seeds so the cycle can 
begin again. 

Now, think what must happen chemically to make this all happen! 

Answer the questions below as thoroughly as you can. Take your time and come up with your 
best answers to these questions. 

1 . Take a look at a Periodic Table of the Elements. What elements do you think are essential for 
plant growth? 

2. Where and how do you think plants get these elements? 

3. Do you think there could be a problem if plants had too little or too much of their required 
nutrients? Explain. 

4. Why do you think farmers and home gardeners use fertilizers? 


5. What is your definition of a fertilizer? 

6. Throughout this unit, you will learn more about the chemistry of plants. What is one thing 
you would like to personally learn about plants and the chemical elements they require? 

7. Read the article(s) provided by your teacher. What are two important issues you think 
farmers, scientists and the general public must address and work on together? 




The purpose of this lesson is to understand the chemistry involved in how plants absorb 


• It is believed that plants require 17 essential elements which can be absorbed only in 
certain forms.2 

A fertilizer is any natural or manufactured material added to soil or water in order to 
supply one or more plant nutrients. 3 

• Fertilizers come in a variety of forms and mixtures of different chemical ions. 

For the Class: 

• 1 copy of The Western Fertilizer Handbook as a reference 

• "Elements Required By Plants" handout 

For Each Group of Students: 

Markers or colored pencils 

Periodic Table of the Elements 

11" X 14" piece of construction paper or butcher paper 

Various references on chemicals, specifically fertilizers 

"Elements Required By Plants" handout (optional) 

For Each Student: 

• "Chemicals, Chemicals Everywhere!" handout 

• "Chemical Formulas and Available Ions In Fertilizers" handout 


1-3 forty-minute session(s) to create and present the "element posters" 

1 forty-minute session to read and complete "Chemical Formulas and Available Ions In 


Prior to this lesson, students will need to know how to use the periodic table, read chemical 
formulas and break compounds down into their ionic components. 

A fertilizer is any type of substance added to the soil or water to increase the nutrients available 
to plants. Plants require 17 essential chemical elements. Three of the 17 elements ~ carbon, 
hydrogen, and oxygen ~ are taken primarily from air and water. The other 14 are normally 
absorbed from the soil or from the particles dissolved in water. Fertilizer is added to soil or 
water to make sure all essential nutrients are readily available in the appropriate forms. The 


14 elements are divided into three groups: primary nutrients, secondary nutrients and 
micronutrients. These groups are based on the relative amounts required for plant growth, yet 
all are equally essential. Primary nutrients are needed in large amounts and are the three 
elements that make up the three numbers on fertilizer packages. These three elements are 
nitrogen, phosphorus and potassium (N-P-K). Secondary nutrients are needed in moderate 
amounts, but not in such quantity as the primary nutrients. The secondary nutrients are 
calcium, magnesium and sulfur. The final category, called micronutrients, are needed by plants 
in very small amounts, yet are critical for plant growth. They are zinc, iron, manganese, 
copper, boron, molybdenum and chlorine. Recently, University of California at Davis research 
indicated that nickel be added to the list of micronutrients. Studies are continuing to determine 
whether or not other micronutrients are needed by plants. 


1. Briefly discuss how chemistry is a part of everyone's daily life. Pass out the handout titled 
"Chemicals, Chemicals Everywhere!" Discuss the chemical compounds and formulas with 
the students. Emphasize the picture of the fertilizer. Explain the three numbers on 
fertilizer labels (the first number is the percent nitrogen, the second number is the 
percent phosphorus and the third number is the percent potassium). Discuss that the 
emphasis the next few days will be on the chemistry of plant nutrients including fertilizers. 

2. Ask the students what elements plants generally absorb from the air. Discuss that they are 
carbon and oxygen in the forms of CO2 and 02- Sometimes plants absorb other substances 
from the air such as sulfur and chlorine but the air is not the major source of these 
elements. Review that plants also absorb hydrogen and oxygen as H2O in gaseous and liquid 
form. Review the basic equations for photosynthesis (6CO2 + 12H2O + 673,000 cal -> 
C6H12O6 + 6H2O + 6O2) and respiration(C6Hi206 + 602 + 6H20^6C02 + 12H2O + 
energy) with your students. Explain the importance of these equations. If you desire, use 
an overhead transparency for this discussion. 

3. Divide your class into 13 equal groups. Assign each group one of the essential plant 
nutrients (excluding C, H, 0). The elements are: nitrogen, potassium, phosphorus, calcium, 
magnesium, sulfur, zinc, iron, manganese, copper, boron, molybdenum and chlorine. 
(Nickel is excluded from this activity, due to it's recent discovery.) Having students draw 
the element names out of a hat randomizes the assignment. Have the students create an 11"X 
14" poster with the information described below. They can obtain this information by 
researching this information in the Western Fertilizer Handbook and other sources. The 
teacher handout "Elements Required By Plants" may be useful if students have difficulty 
locating some of the information. 

The posters should include the following information: 

. Element name 

. Element symbol 

. Category - primary, secondary or micronutrient 

• Forms in which plants absorb the element 

Functions of the element 

Deficiency symptoms if element is not present or is in low supply 
. Toxicity symptoms if element quantity is too high 


Other information the students should include in their brief oral presentation is described 
below. This information can be found in basic plant nutrient books in the school library. 

How does this element naturally exist in nature? 

If the soil does not have enough of this element, how do people provide it to plants? 

What environmental, including agricultural, issues might be associated with this 


Example Calcium Poster: 



Secondary Plant Nutrient 
Function: Essential to healthy cell walls 
Absorbed as the calcium ion Ca 2+ 
Deficiency Symptoms: 

1 . Death of growing points 

2. Abnormal dark green color 

3. Weakened stems 
Toxicity Symptoms: 

1. Brown or white spotting on fruit 

Points for Discussion: 

Common manufactured fertilizers produced from 
phosphate rock contain absorbable calcium. Generally, a 
store-bought manufactured fertilizer contains enough 
calcium for household gardens. Calcium can also be 
obtained from lime and gypsum rock. Areas must be 
mined to get phosphate rock, lime and gypsum. Manures 
and irrigation water have some calcium. Soils high in 
calcium- are easier to till than those low in calcium. 

4. Have each group report their findings to the class. 

5. Display the posters around the room. Refer to the posters at appropriate times during this 
unit and in other appropriate discussions, 

6. Complete the worksheet "Chemical Formulas and Available Ions in Fertilizers" with your 
students. An answer key is provided for your convenience. 



Seventeen elements are required for plants to grow and reproduce. To be utilized by plants, 
each element must be in a certain ionic form. There are many issues and challenges associated 
with plant nutrient uptake, fertilizers, soil amendments and the environment. 


1 . Use fast growing seeds to set up a nutrient assay. Grow plants in complete and deficient 
media. See various science catalogs for kits that provide solutions to create nutrient 

2. Use the CD rom "Plant Requirements" by Technical Publications to learn the importance of 

certain elements. 


1. Have students research what legumes are and how they affect the usable nitrogen level in 

2. Obtain pictures or actual plants that exhibit deficiency symptoms. Incorporate the examples 
into student presentations. 

3. Have students research the importance of proper nutrients in hydroponic systems. 

4. Build a fertilizer model using toothpicks and colored marshmallows or molecular model kits. 

1 7 


(Student Handout) 

Water H,0 

H O 


\/-£ s , .C-OH 

0© lOl 


H" ^C^ ^O— C— CH, 

Vodka CHjCH,OH 

CH, CH, 
CHj-CH 2 -CH 2 -CH,— C H-C H-C H, , others 

Odor of rotten eggs H 2 S 



H C O v H HOCH, O v 

7/1 \ I I .--" 



^X OH H /S 9\ H HO 

Sugar | | I I * 


Fertilizer SH 4 NO,,K ; S04. NH » 

Styrofoam cup 

— CH — CH,- 


CH <._ -C 


CH, CH \ 
I I CH, 

,CH CH^ CH^ / 

c ror v ' 

Birth control pills CHjO CH CH 2 



NO : .NO.S0 2 ,Oj,CO.S0 3 

CH 3 C 


iG»P I CH, (CH,) N Cf , others 

1 y OK 

O - O - N O 



-(CHj — C=CH— CH 2 ) 

Automobile tire 

CH,- C 

' O H 




(Teacher Information) 

I. Introduction 

It is a known fact that humans require certain elements for healthy normal growth. When 
any of these elements are left out of the diet, the body develops definite symptoms which may 
be related to its shortage. Deficiencies of this sort present themselves in abnormalities in 
the growth of body tissues, especially the skin, hair, teeth and bones. 

Plants also have elements which are absolutely necessary for their normal growth, and 
many of these are the same as those required by humans. Nutrient tests may be conducted 
with such plants as corn, beans, tomato and barley to enable students to observe symptoms 
which develop on plants due to the lack of a particular element. 

In addition to carbon, hydrogen and oxygen -- which plants get from the air and water -- 
there are fourteen elements required by plants. These are usually divided into three classes: 

Element Names 

Class 1 



Primary Elements 




Secondary Elements 









Micronutrient Elements (needed in minute 
amounts; excess may be toxic) 

I. Functions of Elements in Plant Metabolism and Symptoms Related to Their 


Function - promotes rapid vegetative growth and gives plants a healthy green color. 


Symptoms - stunted growth, pale yellowish color starting at older leaves, burning of tips 
and margins of leaves starting at bottom of plant. 

Absorbed - NO3-, NH 4 + 



Function - stimulates early growth and root formation, hastens maturity, promotes seed 
production, makes plants hardy. 


Symptoms - slow growth, poor root development, spindly stalk, delayed maturity, 

purplish discoloration of leaves on certain plants, dying of tips of older 

leaves, poor fruit and seed development. 

Absorbed - H2PO4-, HP0 4 2 " 




Absorbed - 
Function - 

improves plant's ability to resist disease and cold, aids in the production of 
carbohydrates and proteins, an active part of enzyme systems. 

slow growth: margins of leaves develop a "scorched" effect starting on older 
leaves, weak stalk, shriveled seed or fruit. 

K + 

aids in the movement of carbohydrates in plants, essential to healthy cell 
walls and root structure. 


Symptoms - terminal bud dies under severe deficiency, margins of younger leaves 
scalloped, blooms shed prematurely, weak stem structure. 

Absorbed - Ca 2+ 


Function - is an ingredient of chlorophyll, aids in the translocation of starch within 
plant, essential for the formation of oils and fats. 



yellowing of leaves between veins starting with lower leaves, leaves 
abnormally thin, tissue may dry and die, leaves have a tendency to curl 





Function - aids in the formation of oils and certain proteins. 


Symptoms - lower leaves yellow-green, stems and roots small, entire plant tends to be 

Absorbed - SO4 2 - 


Function - aids in the assimilation of calcium; amount required is extremely small. 


Symptoms - affects tip growth, cracked stems in celery, small heads in cauliflower. 

Absorbed - B03 3- 


Function - promotes formation of Vitamin A; excess is very toxic. 


Symptoms - bleached appearance of leaves, die-back of new growth in citrus. 

Absorbed - cu+, Cu 2+ 


Function - essential in the formation of chlorophyll and in the release of energy from 


Symptoms - yellowing of leaves (young leaves first), veins remain green, affected leaves 
curl upward. 

Absorbed - Fe 2+ 


Function - acts as a catalyst in plant growth processes. 


Symptoms - chlorosis between veins of young leaves, dead spots in affected tissue, dwarf 
appearance of plant. 

Absorbed - Mn 2+ 



Function - aids plant in using nitrogen. 


Symptoms - stunted and yellow in color (resembles nitrogen-deficient plant). 

Absorbed - M0O4 2 " 


Function - aids in the formation of chlorophyll and carbohydrates. 


Symptoms - small chlorotic leaves ("Little-leaf" in citrus), reduced fruit formation, 
die-back of twigs after first year. 

Absorbed -Zn 2+ 


Function - stimulates manufacture of carbohydrates and chlorophyll, helps regulate 
water balance in plants. 


Symptoms - slightly wilted appearance. 

Absorbed - CI" 


Function - recently discovered to be an essential trace element; details on its function, 
deficiency symptoms, etc. are still being researched. 


Student Worksheet Name 



Soil serves as a storehouse for plant nutrients and normally provides plants with the nutrients 
they require to grow and reproduce. Under most conditions, however, growth can be enhanced 
by the proper application of supplemental nutrients especially when plants are grown in areas 
where they are not naturally grown or when plants are grown in heavily farmed areas where 
nutrients are not replaced as quickly as they are removed. Nutrients are removed from the soil 
when crops are harvested for food. Thus, fertilizers are used to replenish the soil. 

Nutrients can be added to soil in many ways. The earliest fertilizer materials were animal 
manures, plant and animal residues, ground bones and potash salts (wood ashes). These 
substances are still used to amend soils today. Three major developments in the nineteenth 
century were the forerunners of the modern fertilizer industry and promoted the mass 
production of fertilizers as we know them today. 

18 39- The discovery of potassium salt deposits in German states. 

1842- The treatment of ground phosphate rock with sulfuric acid to form super 

1884- The development of the theoretical principles for combining hydrogen and 

atmospheric nitrogen to form ammonia. 

Fertilizers are categorized by how much of the primary nutrients they contain. A single 
nutrient fertilizer has one primary nutrient. A multinutrient fertilizer has two or more of the 
primary nutrients. The three numbers on a fertilizer label represent the percentages of 
nitrogen, phosphorus and potassium, in that order. 

When fertilizers are incorporated into the soil, they are absorbed in their ionic forms. The 
compounds in the following list are used to form fertilizers or are fertilizers themselves. Read 
the chemical formulas and write their chemical names in the appropriate places on the chart. 
Break the compounds into their positive and negative ions and complete the remainder of the 









(NH 4 ) 2 HP0 4 


Ca(N0 3 )2 


Ca(CN) 2 


NaN0 3 












CuS0 4 


FeSO 4 -7H 2 






Na2Mo0 4 H2O 


ZnSO 4 -H 2 




ZnCI 2 

Compare the ions in the chart above to the essential plant nutrient ions that plants absorb. 
Which of the chemical formulas contain ions that plant roots can absorb? 










Ammonium Nitrate 

NH 4 + 



(NH 4 ) 2 HP0 4 


NH 4 + 

HP0 4 2- 


Ca(N0 3 ) 2 

Calcium nitrate 

Ca2 + 

N0 3 " 


Ca(CN) 2 

Calcium Cyanamide 

Ca 2+ 




Sodium nitrate 

Na + 




Phosphoric acid 

H + 

po 4 3 - 



Potassium chloride 

K + 




Potassium nitrate 

K + 

N0 3 - 


K 2 S0 4 

Potassium sulfate 

K + 

S0 4 2- 



Copper (II) oxide 



11. ( 


Copper (II) sulfate 

Cu 2+ 

S0 4 2" 


FeSO 4 -7H 2 

Iron (II) sulfate 


S04 2 - 



Manganous sulfate 

Mn2 + 

S0 4 2- 


MnCI 2 

Manganous chloride 

Mn2 + 



Na2Mo04 H2O 

Sodium molybdate 

Na + 

Mo0 4 2 " 


ZnSO 4 -H 2 

Zinc sulfate 


S0 4 2 - 



Zinc oxide 





Zinc chloride 

Zn2 + 






As consumers, students need to learn how to make educated decisions about the products they 
buy. This activity will teach students how to make knowledgeable decisions about the purchase 
of fertilizers. The students will learn how to calculate the amount of plant nutrients available 
in any given fertilizer and then compare the costs of fertilizers with regard to the amount of 
nutrients that are available to plants. 


All fertilizers do not contain the same percentage of each of the primary nutrients; 
fertilizers are prepared in different compositions so the consumer, farmer or home 
gardener, can apply only what is needed to the soil? 

• Though fertilizers are an important part of crop production over-fertilization and misuse 
of fertilizers can be harmful to the environment? 

• In order to be effective, fertilizers must be used properly. 

For the class: 

• Commercial fertilizer labels (optional) 
Fertilizer label handout (optional) 

For each student: 

• "How to Determine the Percent of A Nutrient Available in a Fertilizer" worksheet 
. Calculator 

. Periodic Table 


forty-minute session 


Farmers decide what fertilizers to apply examining the soil type, soil quality and the plant crop 
requirements. First, the particular soil is tested to see what nutrients need to be added to the 
soil. The farmer then chooses fertilizer combinations that will best meet the needs of the 
particular situation. Manures, composts, crop rotation with legumes and manufactured 
inorganic fertilizers are options to be considered in an integrated approach to plant nutrient 
supplementation. Underfertilization reduces crop yield. Overfertilization can reduce crop yield 
and can be costly and dangerous to the environment. More and more research is being done to 
reduce the problems of groundwater contamination, salt deposition on soils, etc. The 
agriculture industry realizes that it must do its job in protecting and improving the quality of 
the environment. The current agricultural trend is to make agricultural ecosystems 
sustainable. This means that farmers replace the substances that are removed from an 
ecosystem when a crop is harvested. Organic and inorganic substances are used to do this. 


Chemistry calculations play a big part in determining how much of an element is available in a 
fertilizer and in a particular soil. Farmers also need to analyze fertilizers in order to use the 
most cost efficient ones. As your students complete the worksheet, they will learn how to 
calculate the percentages of various nutrients in a fertilizer and determine the percent yield of 
different fertilizers. They will see how this information is useful to themselves as well as to 
major farming operations. 


The percentage composition of a compound is a statement of the relative mass each element 
contributes to the mass of the compound as a whole. A chemist often compares the percentage 
composition of an unknown compound with the percentage composition calculated from an 
assumed formula. If the percentages agree, it will help to confirm the identity of the unknown. 
This type of calculation will be used in this activity. 

Salt is composed of two elements, sodium and chloride, in a 1 to 1 ratio. The two elements are 
present in the same ratio by mass. Therefore, the percentage of sodium in any sample of sodium 
chloride would be the atomic mass of the element divided by the formula mass and multiplied by 

WJ^NaCr" x 100 = 2^arnu 3 + ai 3 1 S J 5 amir x 100 =~~rx 100 = 39.3% Na 


It is just as easy to calculate the percentage composition of a compound, such as ethanol, where 
more than one atom of an element appears. The formula for ethanol is C2H5OH and its molecular 
mass is 46.1 amu. It can be seen that one ethanol molecule contains two carbon atoms with a 
combined atomic mass of 24.0 amu. Therefore, the percentage of carbon in the compound is: 

7^4 x 100 = 52.1% c 


1 . Review with your students how to determine the percent of an element in a compound and 
how to determine yield. 

2. Complete the worksheet with your students. 


Understanding the chemistry of fertilizers is an important part of agriculture. Home gardeners 
and farmers alike can benefit financially and environmentally if they use basic chemistry and 
mathematics before making decisions about which fertilizers to purchase and apply. 


1 . Before or after this activity, you might want to do the "How to Read A Fertilizer Label" 
lesson from the unit "The Interrelationships of Soil, Water and Fertilizers and How They 
Affect Plant Growth" available from the California Foundation for Agriculture in the 
Classroom. See the Teacher Resources section of this unit for ordering information. 



1. Using the fertilizer label handout provided or actual fertilizer labels, have students create 
realistic questions that classmates answer. 

2. The CD rom "Plant Requirements" by Technical Publications allows students to apply a 

certain percentage of a nutrient to a crop and observe what happens. Have your students 
experiment with different quantities of nutrients on a variety of crops. 



Harmful or fatal if swallowed. 
Keep out of Reach of Children. 

Disposal: Container will not contain toxic 
residues if empty. Remove any additional 

fertilizer before disposal. 
Store in cool, dry place. Product will lose 

nutrient value over time. 

Guaranteed Fertilizer Analysis Statement 

Total N 0% 

5.6% Ammoniacle N 

1.1% Urea N 

1 .3% Water Insoluble N 

Available Phosphoric Acid (P2O5) 12% 

Soluble Potash (K20) 4% 

Calcium (Ca) 8.0% 

Magnesium (Mg) 3.0% 

Sulfur (S) 4.0% 

Boron (B) 0.02% 

Iron (Fe) 0.4% 

Manganese (Mn) 0.05% 

Molybdenum (Mo) 0.0008% 

Zinc (Zn) 0.05% 



Keep out of reach of 

Guaranteed Fertilizer Analysis Statement 

Total N 17% 

4.1% Ammoniacle N 

8.9% Urea N 

4.0% Water Insoluble N 

Available Phosphoric Acid (P2O5) 23% 

Soluble Potash (K20) * 6% 

Derived from: Monoammonium phosphate, urea, methylene 
ureas, muriate of potash 


Keep out of reach of children. 
Harmful if swallowed. 

Guaranteed Fertilizer Analysis Statement 

Total N 12% 

12% UreaN 

Available Phosphoric Acid (P2O5) 6% 

Soluble Potash (K20) 6% 

Iron (Fe) 0.5% 

Zinc (Zn) 0.1% 

Primary Nutrients from Urea and Potassium Phosphate 

Trace Nutrients from Iron Sulfate and Zinc Sulfate 

Directions: Add 1 Tablespoon per gallon of water. Apply to 
foliage and soil. Repeat monthly. Do not apply during heat of 


Student Handout Name 


1 . Ammonium nitrate is used as a fertilizer; ammonia is also used as a fertilizer. Compute the 
percentage of nitrogen in each. If both cost the same amount per ton, which is the better buy 
in nitrogen content? 

A farmer has two different fertilizers in her barn. One is K2SO4 and the other is KCI. The 
two fertilizers cost the same per ton, but she wants to use the one with the highest 
percentage of potassium. Which fertilizer should she use? Substantiate your explanation 
with numbers. 

3. Most states mandate that "Guaranteed Fertilizer Analysis Statements" be printed in a 
standard format on all fertilizers. However, if the fertilizer label were not available, you 
might use something like the numbers below to determine whether or not substances were 
comparable in content. Determine whether or not the following samples are the same 

a 45.0 g sample containing 35.1 g Fe and 9.9 g S04 
215.0 g sample containing 167.7 g Fe and 47.3 g S04 

b. 75.0 g sample containing 20.5 g K and 54.5 g CI 
135 g sample containing 67.5 g K and 67.5 g CI 

4. Calcium nitrate and ammonium nitrate are used as fertilizers. Compute the percent 

nitrogen in each. If calcium nitrate costs $225 per ton and ammonium nitrate costs $275 
per ton, which fertilizer is more cost effective? (Hint: Determine the per pound cost of 
nitrogen for each compound.) 


5. Animal manures are often used to add nutrients to soils. Assume that the average price for 
chicken manure is $15 per ton and contains 31 lbs of nitrogen per ton. 

a What percentage nitrogen does the manure contain? 

b. What is the cost per pound of nitrogen? 

c. Which is more cost effective-to apply chicken manure, calcium nitrate or ammonia 

nitrate? Explain. 

d. What are some issues, other than price, that might affect which of the fertilizers a 
farmer or gardener might choose to use? 

6. "Super phosphate" fertilizer is made by treating phosphate rock, Ca3(P04)2 with sulfuric 
acid according to this equation. 

Ca3(P0 4 )2 + 2H2SO4 -» Ca(H 2 P0 4 ) 2 + 2CaS04 

If this reaction has a 52.5% yield, how much Ca(H2P04)2 could be obtained from 5.2 
metric tons of phosphate rock? 

7. Review the questions and answers in the problems above. How could this type of information 
help you as a home gardener? Why is it crucial that farmers understand how to do basic 
chemistry such as this? 




1 . Ammonium nitrate is used as a fertilizer; ammonia is also used as a fertilizer. Compute the 
percentage of nitrogen in each. If both cost the same amount per ton, which is the better buy 
in nitrogen content? 

Ammonium nitrate -NH4NO3 



H 4 

4 x 1 .0079 = 





3 X 15.9994 = 



Ammonia -NH3 
N 14.0067 

H 3X1 .0079= 3.0237 

%N= 8^04^ X 10 ° 

_ 14.0067 
/oN "1 7.0304 X 10 ° 

%N = 34.99 -» 35%N 
for Ammonium Nitrate 

%N = 82.2%N 
for Ammonia 

Ammonia (NH3) is the better buy. It is applied as anhydrous ammonia, a colorless gas. The 
gas is injected into the soil, usually about 5 inches deep. While ammonia is the cheapest 
source of N, marty safetycpreaautions mustbeaisealiin ite applications e v e r e 
eye, nose, throat, lung and skin damage if the applicator comes into contact with the gas. 
Students should understand that factors other than price are considered in selecting nitrogen 

2. A farmer has two different fertilizers in her barn. One is K2SO4 and the other is KCI. The 
two fertilizers cost the same per ton but she wants to use the one with the highest percentage 
of potassium. Which fertilizer should she use? Substantiate your explanation with 






2 X 39.0983 = 
4 x 15.9994 = 


K 39.0983 
CI 35.453 


= 158.2548 * 1UU 

%K -**« X100 


= 49.4% 

%K = 52.4% 

The farmer would get a better buy if KCI was used. 


KEY (continued) 

3. Most states mandate that "Guaranteed Fertilizer Analysis Statements" be printed in a 
standard format on all fertilizers. However, if the fertilizer label were not available, you 
might use something like the numbers below to determine whether or not substances were 
comparable in content. Determine whether or not the following samples are the same 

a 45.0 g sample containing 35.1 g Fe and 9.9 g S04 
215.0 g sample containing 167.7 g Fe and 47.3 g S04 

Ti 1 QQ 

%Fe =r~- X 100 = 78% %S0 4 =^X 100 = 22% 

b. 75.0 g sample containing 20.5 g K and 54.5 g CI 
135 g sample containing 67.5 g K and 67.5 g CI 

%Fe --¥¥s^ X 100 = 78% %S0 4 =^7f X 100 = 22% 

The compounds are the same. 

4. Calcium nitrate and ammonium nitrate are used as fertilizers. Compute the percent nitrate 
in each. If calcium nitrate costs $225 per ton and ammonium nitrate costs $275 per ton, 
what fertilizer is more cost effective if you want to put on as much nitrogen as possible? 
(Hint: Determine the per pound cost of nitrogen for each compound.) 

First to solve this problem you need to find the %N in each material - similar to question 
# 1 . 

Ca(N03)2 NH4NO3 

Gl 40 N 2X14 28 

N2X14 28 H4X1 4 

6X 16 _96 3X16 4 8 

164 80 

%N =~J~; x 100 = 17.1% %N =tt X 100 = 35% 

164 80 

For every ton of calcium nitrate, only 17.1% is the desired, needed nitrogen. Therefore, for 
every 2,000 lbs of calcium nitrate, only 0.171 X 2000) or 342 lbs are actually nitrogen. 
For ammonium nitrate, 35% of the compound is nitrogen, so a ton of ammonium nitrate has 
(0.35 x 2000) = 700 lbs of actual nitrogen. 

To calculate which is more cost effective, you take the cost of each material per pound of 
actual N in each material - 


KEY (continued) 

t f M ■ , ■ - t t $225 2000 lbs Ca(NQ 3 ) 2 $225 

cost of N m calcium nitrate = 2000 lbs Ca(N0 3 ) 2 X 342 lbs N = 342 lbs N= 

.658 = 66 cents per pound N 

For ammonium nitrate, 35% of the compound is nitrogen or 700 lbs N for every ton of 

If ammonium nitrate is $275 per ton: 

♦ * m ■ ■♦ ♦ $275 „ tonofNH4N03 $275 nnnnu 

cost of N ,n ammonium nitrate = ton ^ |H4N53 X 70Q |bs N = 700 lbs N = -039/lb 


Ammonium nitrate = 4 cents per pound of N 

The basic premise is that cost per ton of material and % N must be used to determine which 
N source is most cost effective. In this case, even though NH4NO3 costs more for a ton of 
material ($275 vs. $225/ton of material), it has a lot more N (35T N vs. 17.1% N in 
calcium nitrate). This high concentration of N spreads the cost out and makes NH4NO3 a 
cheaper source of desired N (4 cents per pound N vs. 66 cents per pound of N in Ca(NC>3)2.) 

This same theory applies to the consumer at the grocery store. Should you buy a whole 
chicken (with inedible bones and skin and neck, wings, etc.) for $1 .50 per pound or buy 
boneless, skinless, all white meat chicken breasts for $2.50 per pound? Which one is the 
best buy of desirable, usable, edible chicken? 

Animal manures are often used to add nutrients to soils. Assume that the average price for 
chicken manure is $15 per ton and contains 31 lbs of nitrogen per ton. 

a What percentage nitrogen does the manure contain? 

2000 lbs '° 155 - 0155 x 10 ° = 1 - 55% nitr °g en 

b. What is the cost per pound of nitrogen? 

$ 1 5 w I t n „ 2000 lbs * AnA „^ KI 

1^ton X 2000 lbs ^Wlb^ = $ ' 484/lb N = 48C P er P° und 

c. Which is more cost effective-to apply chicken manure, calcium nitrate or ammonia 

nitrate? Explain. 

Ammonium nitrate is more cost effective 
chicken manure = 480 per pound 
calcium nitrate = 660 per pound 
ammonium nitrate = 40 per pound 


KEY (continued) 

d. What are some issues, other than price, that might affect which of the fertilizers a 
farmer or gardener might choose to use? 


ease of application 

reduced nitrogen loss to the environment 

effect on soil microbes 

effect on soil organic matter 

plant's need for other nutrients 

availability of nitrogen for immediate and/or delayed uptake by plants 

transportation costs 

6. "Super phosphate" fertilizer is made by treating phosphate rock, Ca3(P04)2, with sulfuric 
acid according to this equation. 

Ca3(P0 4 )2 + 2H2SO4 -» Ca(H 2 P0 4 )2 + 2CaS04 

If this reaction has a 52.5% yield, how much Ca(H2P04)2 could be obtained from 5.2 
metric tons of phosphate rock? 

, ■ , w « r « r x, molecular mass of Ca(H2P04)2 
5.2 metric tons X 0.525 X mo | ecu |ar mass of Ca 3 (P0 4 )2 

7. Review the questions and answers in the problems above. How could this type of information 
help you as a home gardener? Why is it crucial that farmers understand how to do basic 
chemistry such as this? 

Answers will vary. 




The purpose of this activity is for students to experience making a fertilizer and then to 
quantitatively test for a particular component, phosphate, in fertilizers. 


Fertilizers are made in a variety of ways. 4 

Fertilizers contain elements and can be tested to measure the amounts of those elements. 

Fertilizers do not all contain the same percentages of each of the primary nutrients; 
fertilizers are prepared in different compositions so the consumer, farmer or home 
gardener, can apply only what is needed to the soil.5 


For each student: 

"Making A Fertilizer" and "Phosphate Analysis of Fertilizers" worksheets 
For the entire class: 
"Making a Fertilizer": 

• NH4NO3 . Stoppers to fit flasks 

• KH2PO4 • Balances 

• KCI . Filter paper 

• Flasks-- 1 per team • Distilled water 

"Phosphate Analysis of Fertilizers": (materials listed are for 30 students in teams of two): 

20 g ascorbic acid 

20 g commercial fertilizer having a 20% phosphate content 

1 .0 L of 10.0 ppm standard phosphate buffer solution (65 mL/team) 

1 g potassium phosphate, di-basic (K2HPO4) for preparing standard phosphate buffer 

solution; fw= 174.18 as anhydrous K2HPO4 (see advance preparation) 

300 mL ammonium molybdate-sulfuric acid reagent (see advance preparation) 

7.5 g ammonium molybdate (NH4)2Mo04 crystals for preparing reagent 

150 mLconc. sulfuric acid for preparing reagent 

10 liters distilled water 

105 test tubes (19mmx 150mm)- 6 per team 

1 5 test tube clamps 

15 ringstands, ring clamps, wire gauze 

15 500 mL beakers 

15 250 mL beakers 

15 10 mL graduated cylinders 

15 5mL or 1 00-mL cylinders 

15 500mL flasks 

15 stirring rods 

15 Bunsen burners 

balance with filter paper 



2 class periods 


Phosphate rock deposits are the basic source of all phosphate materials. The earth has many 
natural deposits of phosphate which are igneous or sedimentary in origin. The predominant 
phosphate mineral is francolite, a carbonate fluorapatite represented by the formula 
Ca-|()F2(P04)6 • CaC03. Most of the world's reserves now being mined are in North Africa, 
North America and Russia. The phosphate mines in the western states are located in Montana, 
Idaho, Utah and Wyoming. Florida, North Carolina and Tennessee also have phosphate rock 
deposits. Phosphate rock must be converted to a phosphate form which can be utilized by plants. 
Most phosphate rock contains 14 to 35 percent phosphate; therefore, it must be concentrated to 
process into fertilizers. One common method of doing this is by exposing the phosphate rock to 
sulfuric acid and water as shown in the simplified chemical equation below: 

Cal 0F2(PO4)6 + 1 ° H2SO4 + 20 H20 -* 10 CaS0 4 . 2 H20 + 2 HF + 6 H3PO4 

phosphate + sulfuric + water -» calcium + water + hydrogen + phosphoric 

rock acid sulfate (gypsum) fluoride acid 




The standard phosphate solution is prepared by dissolving 1 .0g K2HPO4 in a small volume 
of water and then diluting to 1000 mL in a volumetric flask. Mix. Take 20 mL of this 
solution and dilute to 1000 mL. This produces one liter of standard (10.0 ppm) phosphate 


The ammonium molybdate-sulfuric acid reagent is prepared as follows. 

Dissolve 7.5 g of ammonium molybdate in 75 mL of distilled water. Cool the solution in 

an ice bath. Retain this solution for a later step. 

Slowly, while mixing, add 125 mL of ice-cold 18 M H2S04to 125 mL of ice-cold 

distilled water. (Caution: Diluting concentrated sulfuric acid generates considerable 

heat, and may produce splattering if not added slowly with continual stirring. Perform 

this dilution with considerable care.) 

Slowly, while mixing, add the cold sulfuric acid solution to the ice-cold ammonium 

molybdate solution. Keep the ammonium molybdate solution in an ice bath during this 

step. This makes up the 325 mL reagent solution. 


Buy a fertilizer that has a 20% phosphate content (N-P-K). This will be Fertilizer "X" in the 



1. Discuss with students the different ways of producing fertilizers (See background 
information and also refer to the Western Fertilizer Handbook) . Tell them that they will be 
making a simple liquid fertilizer. 

2. Have students complete the lab. 

3. Make sure your students save their fertilizers for the next activity. 

1. Discuss the purpose of this activity with your students. (See purpose and background 
information as well as student lab.) 

2. After reviewing safety precautions, have students complete the lab. 

3. Discuss ways, other than colorimeters, of identifying ions in particular substances. 

4. After the students have completed the experiments, relate their findings to the global 
agricultural picture. Center the discussion around the post-lab questions which emphasize 
the importance of colorimetric techniques, student connections to everyday observations of 
the color density of solutions and the practical significance of quantitative data to a farmer. 

Lab Tips 

. The actual value of phosphate, as phosphorus (V) oxide ,P205, using 20-20-20 fertilizer 
is 20%. 

. Fertilizer "X" will range between 17-25% phosphate (P2O5). 

The intensity of the color is affected by the length of time the solution is allowed to boil; 
some consistent method of heating must be agreed upon to insure comparable results 
throughout the class. The point at which the first "bump" of boiling occurs is an acceptable 
reference point. 

• With a spectrophotometer, data can be collected and plotted to obtain an absorption curve for 
the phosphate standards. This curve can then be used to compare sample values with the 
standards. A wavelength of 610 nm gives optimum absorption for this experiment. 


Fertilizers are made in a variety of ways and contain a variety of components in various 
concentrations. Fertilizers can be produced to contain certain ions that are required by plants 
in specific quantities and these ions can be measured using a variety of techniques including 
colorimeters. The chemical production and analysis of fertilizers is crucial to the viability of 
farmers as well as the environment. 



1. Have a discussion about phosphorus. Perhaps a fertilizer manufacturer representative 
and/or farmer can discuss some of this information with your students. Some possible 
questions are listed below. 

Where does phosphorus come from? 
How is phosphorus formed in nature? 
Where are phosphate deposits located? 

What soil types and weather conditions are needed for phosphorus deposit formation? 
Are there phosphorus mines located in California? 
What are some non-agricultural uses of phosphorus? 
Once mined, how is phosphorus formulated for agricultural use? 
What are the functions of phosphorus in plant and animal systems? 
What quantity of phosphate rock is mined each year? 

Is the phosphorus supply considered to be endless? If not, predict when human use will 
exceed phosphorus reserves. 
• What are alternatives to mining phosphate rock to obtain useful phosphorus? 

2. Have students plant corn or wheat seeds. Water some with tap water, some with class-made 
fertilizers and some with store-bought fertilizers. Compare the results. 

3. Prepare four different fertilizers-one without nitrogen, one without potassium, one 
without phosphorus, and one with all three. Use the fertilizers on plants and observe 
growth variations due to nutrient deficiencies. 

4. Use the "waste" fertilizers from the experiment on school landscaping. 

(Lab activities adapted from ChemCom . a high school chemistry book, with permission.) 


Student Handout Name 


All plants require certain nutrients in order to grow. However, the amount required varies 
from plant type to plant type. For example, asparagus requires approximately half as much 
nitrogen, 65% of the phosphorus and 50% of the potassium that almonds require. Therefore, an 
almond farmer will need to use a different composition fertilizer than an asparagus grower if 
nutrients are to be applied in the needed quantities. Proper application of appropriate 
fertilizers benefits farmers financially as well as protects soil, water and air quality. 

Your group will formulate one of two liquid fertilizers. The two liquid fertilizers will have 
different compositions. As you complete the procedure, keep in mind how your research could 
benefit agriculture. 



1. Group A will produce a fertilizer as follows: 

a Combine 7.1gNH4N03,4.8gKH2P04 and 1.4g KCI with a mortar and pestle, 
b. Take 0.5g of mixture and put in 500 ml flask. Add enough water to produce 500 ml 
of solution. 

Group B will produce a fertilizer as follows: 

a Combine 4.8gKH2P04 and 1.4g KCI with a mortar and pestle, 
b. Put 0.5g of mixture into 500 mL flask. Add enough water to the mixture to produce 
500ml of solution. 

2. Save the fertilizer you prepared for the next activity! 

3. Complete the "Let's Think About It" section. 



1 . Legumes, such as peas, beans and peanuts, have a unique mutualistic relationship with 
certain bacteria that live in nodules on the roots of these plants. The bacteria are able to 
convert atmospheric nitrogen (N2), a form of nitrogen that plants cannot absorb, into 

ammonium ions (NH4 + ), a form of nitrogen that plant roots can absorb. For this reason, 
most legumes do not require nitrogen to be added to the soil in order to grow. 

Suppose you are a farmer. Last season you grew corn on a particular plot of land. You have 
decided to grow beans on the land this season. The bean plants will be tilled into the soil 
after harvest. They will not only add nitrogen back into the soil, they will also add organic 
matter which will make the soil more viable, thus improving water holding capacity, 
infiltration and tilth. 

Review the compositions of both fertilizers that your class made. Which fertilizer (A or B) 
should the farmer use on the beans, or does it matter? Explain your reasoning. 

2. The fertilizer you made was a liquid. Fertilizers are also applied as solids and gases. 

Describe a situation where you think a solid or gaseous fertilizer would be a more 
appropriate form of fertilizer. How do you think gaseous and solid fertilizers are made? 
How are they applied to the soil? 


Student Handout Name 



Most fertilizer packages list the percents (by mass) of the essential nutrients contained in the 
fertilizer. In this activity you will determine the mass and percent of phosphate ion in various 
fertilizer solutions. The method you will use, called a colorimetric method, is based on the 
fact that the intensity of a solution's color indicates the concentration of the colored substance. 
A chemical reaction will convert colorless phosphate ions (PO4 3 ") to colored ions. To 
determine the percent of phosphate ion present, you will compare the color of the unknown 
solutions to colors of solutions with known concentrations. 



Note: You will prepare the unknown fertilizer solution by diluting the fertilizer "X" by a factor 
of 50. This dilutes it enough for comparison with the color standards you will have. You will 
also dilute the fertilizers A and B you and your classmates prepared by a factor of 50. 

1. Label 7 test tubes as follows: 10 ppm, 7.5 ppm, 5 ppm, 2.5 ppm, Fertilizer A, Fertilizer 

B, and X. (ppm=parts per million) 

2. Complete these steps to prepare the unknown fertilizer "X" solution: 

a Place 0.50 g of fertilizer "X" in a 400 mL beaker. Label the beaker "original." 
b. Add 250 mL of distilled water. Stir until the fertilizer is completely dissolved. 

C. Pour 5.0 mL of this solution into a clean dry 400 mL beaker labeled "dilute." Discard 
the remaining 245 mL of the "original" solution in the container provided by your 

d. Add 245 mL of distilled water to the 5.0 mL solution in the dilute beaker. Stir to mix. 

3. Pour 20 mL of the diluted solution into the test tube labeled "X". Discard the remaining 
diluted solution in the container provided by your instructor. 

4. Complete these steps to prepare the Class Fertilizer A . 

a Place 5.0 mL of fertilizer A in a clean, dry 400 mL beaker and to it add 245 mL of 
distilled water. 

b. Label the beaker "A". 

c. Pour 20mL of the "A" solution into the test tube labeled "A". Discard the remaining 
solution in the container provided by your instructor. 

5. Complete the steps described in #4 above, with Class Fertilizer B. 


In the tube labeled 10 ppm, place 20 mL of the standard 10 ppm phosphate ion solution 
provided by your teacher. Add solutions and water to the other three test tubes as listed 

Concentration (ppm) 

Standard 10 ppm phosphate 
solution (mL) 

Distilled Water (mL) 












7. Add 2 mL of ammonium molybdate-sulfuric acid reagent to each of the four prepared 
standards, the unknown (X), and the class fertilizers "A" and "B." 

8. Add a few crystals of ascorbic acid to each tube. Stir to dissolve. 

9. Prepare a water bath by adding about 200 mL of tap water to a 400 mL beaker. Place the 
beaker on a ring stand above a Bunsen burner. Place the 7 test tubes in the water bath. 

10 Heat the water bath containing the test tubes until a blue color develops in the 2.5 ppm 
solution. Turn off the burner. 

1 1 . Allow the test tubes to cool briefly. Using a test tube holder, remove the test tubes from the 
water bath and place them numerically in a test tube rack. 

12. Compare the color of the unknown solution with those of the standard solutions. Place the 
unknown "X" between the standard solutions with the closest matching colors. Do the same 
for the test tubes labeled "A" and "B." 

13. Estimate the concentration (ppm) of the unknown solution and the two class solutions, "A" 
and "B", by comparing the solutions to the known concentrations of the color standards. 
(For example, if the unknown solution color falls between 5 ppm and 7.5 ppm color 
standards, you might decide to call it 6 ppm, or 6 g phosphate ion per 10 6 g solution). 
Record the estimated values of each of the substances by creating an easy to read table of 
your own creation. 

1 4. Clean up the equipment and wash your hands thoroughly before leaving the laboratory. 


1 . Calculate the mass of phosphate ion in the three fertilizers (X, A and B) using this equation. 
Place the numerical value of the unknown solution concentration (in ppm) in the blank. 

mass of P04 3 *(g) = 

gPQ4 3 ' 

10 6 g solution 

x 250g solution x 50 

The factor of 50 in the calculation takes into account the 50-fold dilution of the fertilizer 
solution. By multiplying the calculated mass of phosphate by 50, the mass is adjusted back 
to its pre-diluted value. Record the calculated mass of the phosphate ion. 


2. Calculate the percent phosphate ion (by mass) in the fertilizer sample. Record this value. 

0/ po 3 mass of phosphate ion (step #1 3)x 

/0 PU4 " mass of fertilizer (0.50g) ou 


1. Name two household products or beverages for which you can estimate relative 
concentrations just by observing their color intensity. 

2. Instruments called colorimeters are often used for determining solute concentration. In this 
experiment, phosphate ions are the solute. Colorimeters measure the quantity of light that 
passes through an unknown sample and compares it with the amount of light that passes 
through a known standard solution. 

Colorimeters are used on tomato harvesters. A standard wavelength for the color red is set 
in the colorimeter. Tomatoes pass by the colorimeter as they are harvested. Tomatoes 
which do not have the appropriate color, such as green or yellow tomatoes, are identified by 
the colorimeter and are dropped out of line and dumped back into the field. 

What are the advantages of a colorimeter over the human eye? Why do you suppose tomato 
harvesters still need to have a few people on them to help sort out odd colored tomatoes? 

3. Explain this statement: "The accuracy of colorimetric analysis depends on the care taken in 
preparing the standards." Your fertilizers "A" and "B" should have had 10% phosphate ion. 
How close were you to this number? Where do you think some error factors occurred in 
your experiment? 

Techniques other than colorimetric techniques are used to determine the quantity of certain 
ions. How could a reaction that produces a precipitate be used to determine the concentration 
of an ion? 

5. Why is it important for farmers to know exactly the percent composition of fertilizers they 

6. What risks are involved in applying more nutrient to a soil than is actually needed? 

7. If you were a farmer, what do you think you would do to make sure that you are applying the 
appropriate amounts of nutrients to the soil? What should scientists, agribusinesses, etc. 
do to help you carefully manage your land? 




The purpose of this activity is to allow your students to apply the knowledge they gained to a new 
situation. Career opportunities in agriculture are also addressed. 


The concepts relating to plant nutrient uptakes are extremely complex.* 

Chemistry learned in the classroom is applicable to the real world and affects the lives of all 
people, including farmers and consumers. 

. There are many career opportunities related to agriculture that do not directly involve 
production agriculture. 


For each student: 

1 copy of the "A Letter To Your Grandfather" scenario 


One lo-minute session to introduce the writing assignment 

Two to three nights for students to complete their writing assignment at home 

One 20-minute session to do the concluding activity 


Statistics have shown that many jobs related to agriculture are left unfilled each year due to the 
lack of qualified applicants. It is estimated that 48,000 jobs related to agriculture are 
available each year. However, only 43,500 qualified people are put into the work force each 
year. Agricultural occupations do not include farming only. Only 1-2% of the United States 
population actually farms. Jobs left vacant include positions such as agricultural scientific 
researchers, attorneys, sales personnel, environmental inspectors, etc. The handout "Think 
About It" lists numerous career opportunities that relate to agriculture. Information on how to 
receive a copy of the handout can be obtained by writing the California Foundation for 
Agriculture in the Classroom. 


1 . Discuss the objectives of this activity with your students. 

a) You want them to review the knowledge they gained in the last few days and apply it to a 

new situation. 
b ) You want them to see how chemistry fits into the real world in which they live. 

c ) You want them to think about the challenges that face the environment today and how they 
can be overcome. 

d) You want them to think of career opportunities that are available related to the food we 
eat and the clothes we wear. 


2. Explain to the students that this activity will be used as an evaluation tool to see what the 
students have learned. 

3. Have the students complete this writing activity at home. Encourage students to do many 
rewrites of their letter and to proof them. You may even allow time in class for students to 
proof each other's work. 

4. On the due date of the assignment, have students exchange their letters with one another to 
see what other students have written. Some students may wish to read their letters aloud to 
the class. 

5. Return the "Chemically Speaking - What's in a Plant?" papers the students completed at the 
beginning of this unit. Have students re-read their answers and discuss which of their 
thoughts have changed and which have remained the same. 


The students should conclude that chemistry plays a vital role in production agriculture and 
environmental quality. Many challenges exist in these areas, but with the aid of scientific 
research and technology they can be overcome. 


1 . Have the students complete this activity in small groups. 

2. Have the students present a scientific paper on their research at a hypothetical conference 
titled "Chemistry and Agriculture". 


Student Handout Name 


Put yourself into the situation described below: 

You have lived on a large farm all of your life. The land your family owns has been 
farmed since your great-great-grandparents moved west. 

You have enjoyed the farming operation and feel your family is very successful. Your 
grandfather, however, thinks a little differently. He thinks that the family is 
currently successful but is concerned about food production in the future. He has seen 
tremendous changes in the agricultural industry over the years. He has lived through 
the Dust Bowl era, the changes in pest management, changes in fertilizer production 
and usage and has observed the drastic reduction of prime agricultural land as more 
houses and factories are built. He feels that the family farming operation must be 
updated and that the family must do its part to find out about current issues and trends 
in agriculture. He knows that if the soil, land and air are not properly taken care of, 
your family will not have a future in farming. 

Knowing that you wish to continue the farming operation, your grandfather stated that 
you should attend a two day comprehensive chemistry conference on soil amendments 
and fertilizers. You hesitantly agree to go, not quite sure of how chemistry fits into 

Pretend that the labs, discussions and readings you did the past few days were part of 
this conference. As a farmer, you are amazed at how much the scientific researchers 
do for the world of agriculture and how many challenges are yet to be overcome. 

Your task as a student is to assume the role of the young farmer. Choose one of the two 
assignments described below. 

A) Write a letter to your grandfather explaining what you learned at this seminar. Act 
enthusiastic about the material you learned and about the crucial connections you see 
between farming and science. Discuss the challenges that face agriculture and the 
environment. Mention the different types of people you met at this seminar who spend their 
lives working to make agriculture a viable industry that protects the environment and 
provides safe and plentiful food. 

B ) After attending the conference, you decide to take action on a situation that exists on your 
property. Fifteen to twenty 100 pound bags of fertilizer were delivered to your farm 
during a rainstorm. The labels were destroyed, but the fertilizer is still salvageable. In an 
effort to save money and resources, you decide to determine the fertilizer content and then 
use the fertilizer appropriately. Write an explanation of how you would go about identifying 
the fertilizer - who you would contact, what tests they would do, etc. Also discuss specific 
reasons explaining why you want to identify and use this material rather than discard it. 

Note: This assignment should clearly show your instructor how much knowledge you gained in 
the areas of chemistry, fertilizers and agricultural and environmental awareness. 


Nitrate Debate 

Public concern over nitrates in groundwater 
has the Salinas Valley considering solutions. 

by Caroline Mufford 

itrogen, as every farmer knows, is 
essential to food and fiber produc- 
tion (to say nothing of profits), yet 
it is also a potential source of environmen- 
tal stress. In some cases this stress can in- 
crease under drought conditions. Mini- 
mizing its leakage from the crop root sys- 
tem by avoiding overloading the soil with 
nitrate is the key to reducing the amounts 
of the substance moving to ground and 
surface waters. While nitrates in ground- 
water can hardly be described as a state- 
wide problem, a California Department of 
Food and Agriculture (CDFA) Nitrate 
Working Group report warns, "Several 
regions of California have significantly 
high levels of nitrate in groundwater." 
The report calls for the establishment of 
local management programs in areas with 
high levels of nitrate sensitivity. 

"Whether it's food safety, or environ- 
mental hazards, farmers and ranchers in 
this state have a different burden than in 
other states-that of being a good neigh- 
bor, " says Merlin Fagan, natural re- 
sources director for the California Farm 

Bureau. "If they don't move swiftly to 
solve it, others will." 

While the Environmental Protection 
Agency (EPA) estimates that only a small 
percentage of wells tested have nitrate 
contamination above the federal health ad- 
visory level of 10 parts per million, more 
farmers are seeking reassurance that re- 
sponsible production agriculture will not 
contaminate water. As a result, ConAgra 
Technologies, along with Neogen Corpo- 
ration, has introduced Agri-Screen Nitrate 
test to allow individuals to determine the 
nitrate levels in their water. A simple kit 
is used to test drinking, well and surface 
water as well as water from field runoff or 
tile drainage. (For information on the test 
call 1-800-634-757 1.) 

Monterey County, the "salad bowl" of 
the nation, is one of several areas that 
illustrates the complexities of concerns 
and problems associated with a nitrate 
pocket. Fields of celery, lettuce and other 
shallow-rooted vegetables dominating the 
landscape require high levels of nitrogen. 

Agriculture's visibility, growers and other 
community leaders say, makes it an easy 
target. Some public concerns are real and 
some overblown, but growers are realiz- 
ing they must face them and find educa- 
tional, political and agricultural solutions. 

Monterey County has the most nitrate- 
contaminated drinking water in Califor- 
nia. Of monitored wells, 48 percent show 
unacceptable levels of nitrate contamina- 
tion, according to Monterey County Water 
Resources Agency (MCWRA) figures. 

Matt Zidar, senior county hydrologist, 
says, "We have the largest number of 
small water systems in the state." The 
agency projected in its June 1988 report, 
' 'Nitrates in Groundwater,' ' that ' 'Based 
on the trend of the last 10 years, the pro- 
jected mean nitrate concentrations will ex- 
ceed the drinking water standard in the 
year 2000 by 1.9 to 4.4 times in all uncon- 
fined subareas." This projection is based 
on 90 comparison wells. The drought, 
now in its fifth year, worsens contamina- 
tion because of lack of "recharge" to 
See Nitrate, Page 11 

Page I 


Continued From Page I 

aquifers, says Russ Jeffries, the mayor of 
Salinas. "If it had not been for not having 
any rain for the last five years, personally 
I don't think we'd even be talking about 
[nitrate contamination],*' says grower Sid 
Christierson of Major Farms. 

Controversy over nitrates in Monterey 
revolves around money, but the underly- 
ing issues involve much more, including 
public health, real estate development, 
cleanup of drinking water, assignment of 
liability and responsibility for costs and 
the well-being of local agribusiness. For ex- 
ample, one local paper linked Monterey's 
high rate of birth-defect deaths (highest 
among California's 30 large counties) to ni- 
trate pollution in groundwater. 

On the Monterey Peninsula, a recent 
moratorium halted the drilling of new 
wells. The health department cites nitrate 
pollution as the reason, but growers con- 
sider it a no-growth ordinance in disguise. 
"If you know you have nitrate contamina- 
tion on your property, there may be dis- 
closure requirements before a property 
transfer," which could make properties 
unattractive to potential buyers, Zidar ex- 

A major concern revolves around the im- 
minent threat to the aquifer providing drink- 
ing water for Salinas, Monterey's largest 
city, with 106,000 residents. Jeffries says an 
aquifer on the valley's east side that is highly 
contaminated with nitrate is now migrating 
toward an aquifer feeding the city. "Most 
reports point fingers at growers, but there are 

several other points of nitrate contamina- 
tion,' ' Jeffries says. 

Zidar adds that nitrates in groundwater 
are almost impossible to trace. If scientists 
find this kind of contamination underneath 
a 30-year-old feedlot, for instance, they 
can make "an educated guess" that the ni- 
trates come from feedlot animal waste, but 
the complexities of soil and water move- 
ment mean no one can be certain. Tracing 
the origin of the contamination is the first 
order of business in deciding liability for 
cleanup costs. ' 'Nitrate contamination can 
be handled by filtration or reverse osmosis 
of nitrate, but it is very expensive to do. 
Consequently, who is responsible for that 
cost of cleanup?" Jeffries asks. 

Direct costs due to nitrate mitigation for 
Salinas or other sites could include well 
relocation and/or deepening, wellhead 
treatment to remove nitrogen, and the im- 
porting of water for dilution. According to 
1989 estimates by the Orange County 
Water District, the wellhead treatment 
process for nitrate removal costs about 
$375 per million gallons. In 1986, 
California's Department of Health Ser- 
vices says it received requests for reme- 
dial measures for nitrate of $48.7 million. 
Many water systems do not apply for 
funding, so total funds expended for ni- 
trate mitigation may run higher. 

Benny Jefferson, a grower of cauli- 
flower, head lettuce, celery, and mixed let- 
tuces, says many growers will have 
increased costs for their water systems. 
"The Monterey County Environmental 
Health Department is going to go around 

and check every single well. If you have 
two houses, and one is [inhabited by] an 
employee, then you are required to have a 
doublecheck valve," he explains. Cliff 
Sharpe, field operations manager with the 
Office of Drinking Water, adds that farm 
families with babies will want to check for 
nitrates in their property's well water. In 
California, Sharpe says, 600,000 to 1 mil- 
lion people depend on private wells for 
drinking water. 

In response to these concerns, the Mon- 
terey County Board of Supervisors in Oc- 
tober 1988 formed the Ad Hoc Salinas 
Valley Nitrate Advisory Committee, com- 
posed of local officials (including Jeffr- 
ies), hydrologists, and ag community 
members. Members expect the report to 
go to the board this spring. 

Jacques Franco, CDFA nitrate manage- 
ment coordinator, says statewide over- 
sight of this contamination is easier than 
it is for local agencies. However, he says, 
nitrate contamination exists as a localized 
problem, varying widely among areas 
within counties. "It's a touchy subject be- 
cause you are dealing with liability, par- 
ticularly at the local level," Franco says. 
"In Monterey I've seen all sorts of funky 
manipulations to sanitize reports. Every- 
body there is under tough pressure to 
come up with the kinds of answers the con- 
stituency is willing to accept." For in- 
stance, he says, Monterey County is 
caught in a squeeze between state and 
local pressures. "The state board has 
power to adjudicate a basin. They have 
SeeNitrate, Page III 

Page II 


Continued From Page II 

threatened the board of supervisors to do 
that if they don't clean up the groundwa- 
ter. Some people say 'let them do it.' " 

The fertilizer industry has been pursuing 
nitrate management, according to Steve 
Beckley, executive vice-president of Cali- 
fornia Fertilizer Association. CFA helped 
set up a fertilizer sales tax to fund Franco's 
program through CDFA. "We want to 
make sure we (the fertilizer industry) are 
[not part] of the problem," Beckley says. 
Many factors contribute to nitrate contami- 
nation, and the complexities of Salinas Val- 
ley provide a good example. Backflow often 
gets fingered, but Jefferson, who serves on 
the nitrate committee, feels the issue is over- 
blown. "Nitrate from wells is over- 
calculated as a problem in this county," he 
says. "No one injects more fertilizer than 
absolutely necessary." Christierson, who 
also is a member of the committee, agrees. 
"We're not going to put on any more fertil- 
izer than we have to . . . Nobody in their 
right mind is going to run fertilizer down a 
well." UC Extension soils specialist Stuart 
Pettygrove says geologic source leaching 
from irrigation water has been incorrectly 
ruled out in Salinas. 

Photographic evidence from the Monte- 
rey area shows, in fact, that active green- 
house operations may be among the 
highest sources of nitrate contamination, 
according to Gerald Snow, water quality 
analyst with MCWRA. Greenhouses his- 
torically use three to four times the nitrate 
as comparable root crops-Snow says 

they flush excess nitrogen. 

For example, the nitrate level in Quail 
Creek, along which a greenhouse is lo- 
cated, often runs up to 1,000-2,000 ppm. 

Evidence also shows that long-running cat- 
tle feedlots may contribute high levels of ni- 
trate. However, Snow contends, feedlots have 
improved their practices in recent years. 

According to Snow, other nitrate "hot 
spots' ' in Monterey County include an 
agrichemical dealer with poor handling 
practices (the dealer has since improved), 
a farm where nitrate fertilizers were si- 
phoned down a well, numerous former 
dairies in the county, and even septic 
tanks. Sandy soils, irrigation and organic 
matter in the soil also affect nitrogen 
movement and levels. 

Growers outside of Monterey County 
will not escape the issue, either, although 
groundwater-nitrate problems, hence 
political pressures, vary tremendously 
among counties. In Fresno County, 
groundwater nitrate values have tested 
above the maximum contaminant level 
(MCL) for years. Last summer, Fresno 
Extension advisors Dan Munk and Pedro 
Ilic found 100 ppm of nitrates in a well 
supplying household drinking water on a 
small farm. However, Munk says, at an- 
other farm two miles away, well water 
measured only 20-15 ppm. Small-farm 
and vegetable advisor Ilic says farmers he 
works with tend to over-fertilize. "The 
Valley has a serious problem with nitrate 
contamination," Ilic says, noting 60 years 
of continuous farming as a factor. "We all 

need to assume we contribute to the prob- 
lem," he warns. 

Sources for rising nitrate levels in Cal- 
ifornia aquifers include greater numbers 
of people generating more sewage, the 
burning of fossil fuels, greater industrial 
sources and greater amount: cf nitrogen 
fertilizer and livestock, CDFA's Nitrate 
Working Group says in its February 1989 
report, "Nitrate and Agriculture in Cali- 

Nationwide, concern over nitrates inter- 
sects other growing public concerns. Con- 
sumers want clean drinking water, local 
and federal governments seek to stop 
groundwater pollution, and everywhere 
urban interests seem to be rubbing against 
those of agriculture. 

"Historically," says Franco, "EPA has 
directed state water quality agencies to- 
ward point-source problems. Most of the 
efforts have been put into these programs 
over the past 20 years. Nonpoint water 
problems are much more complicated, 
technically and politically." 

"Nitrate is ubiquitous in the environ- 
ment," says Pettygrove, of UC-Davis. 
"You can't trace it to a bag of fertilizer.'* 
According to the CDFA report, "Fertil- 
izer applications, when associated with 
porous soils and excessive application of 
irrigation water or in areas with shallow 
water tables, have contributed to the in- 
crease in groundwater nitrates. Addition- 
ally, areas within the state which are 
vulnerable are those where multiple plant- 
See Nitrate, Page 1111 

Page III 


Continued From Page III 

ings of high-nitrogen- requiring, low use- 
efficiency vegetable and truck crops are 
grown. The high nitrogen requirement and 
production of up to three crops a year 
make the total nitrogen applied several 
times the. normal application rate for most 
other systems." 

Last year, Franco says, California initi- 
ated a "nonpoint source" nitrate unit in 
Sacramento, managed by Stan Martinson. 
"I think the pressure [on nitrates] is going 
to come," Franco says. On a federai level, 
the EPA released in November 1990 a 
five-year, $12 million study of drinking- 
water wells in the United States. EPA thus 
started an undoubtedly busy year of 'de- 
bate, as the lo-year-old Clean Water Act 
comes up for reauthorization this year. 
EPA found more than half the wells it 
tested were tainted with nitrates. But it 
found nitrate above the MCL in fewer than 
3 percent of wells. The American Farm 
Bureau states: "Farmers and Farm Bu- 
reaus may be forced to defend themselves 
against headlines that talk about nitrate 
detections even though levels of 0-3 ppm 
nitrate-nitrogen are considered natural 
background levels. EPA did not say how 
many detections were in this natural 

The Salinas Valley experience suggests 
growers can prepare for increasing pressure 
over nitrates by educating themselves as 
well as the public; by political organizing, 
particularly at local or county levels; and 
by a score of agricultural approaches. For 

education, Ilic says Extension offices can 
guide growers to material, adding that new 
publications on nitrates are plentiful. For 
organizing, counties with high groundwa- 
ter nitrates can consider the Salinas Valley 
report recommendations: ' 'A cooperative 
effort between numerous agencies and 
groups will be required. These may in- 
clude the District, the County Agricultural 
Commissioner's Office, agribusiness in- • 
terests, UC Extension Service, the Soil 
Conservation Service, Monterey County' 
Environmental Health Department, the 
Central Coast Regional Water Quality 
Control Board, the State Water Resources 
Control Board, and the CDFA." 

Such a group could institute programs to 
locate abandoned wells and ensure contain- 
ment of polluted water, for example. It also 
could set up a program to educate farm 
workers on fertilizer handling practices. 

The CDFA report from the Nitrate 
Working Group also suggests establish- 
ment of local management programs in 
areas with high levels of nitrate sensitiv- 
ity. It calls for immediate reduction of sig- 
nificantly high levels in several regions of 
California, and recommends CDFA facil- 
itate these five actions: Identify nitrate- 
sensitive areas; list priority areas for ni- 
trate control; set up nitrate management 
programs in these areas with local govern- 
ment and agriculture; develop best-man- 
agement practices to incorporate in these 
local programs; and establish a research 
and demonstration project on nitrate con- 
trol through irrigation, fertilizer, and ma- 
nure management. 

For agricultural approaches, "It's a differ- 
ent prescription for each soil and crop condi- 
tion," Pettygrove says. Munk says one 
eggplant and tomato grower with high nitrate 
• groundwater levels plans to forgo additional 
nitrate applications this year. Grower Jeffer- 
son says, "One of the most important things 
you can do is to make sun your injection 
point for fertilizer for a well is on the down- 
stream side of your checkvalve." Monterey 
invites growers to begin with evaluation of 
their irrigation systems, since water use is in- 
tegral to nitrate movement. The county has 
available a new mobile lab to offer free, no- 
obligation evaluations. 

To growers who feel beleaguered over 
nitrates, Franco reminds them the same 
programs can be seen as environmentally 
motivated, "bottom-line enhancement. En- 
ergy savings, water savings and water 
quality-all these goals are aligned when 
you reduce water contamination from 

Printed with permission from the 

California Department of Food and 

Agriculture's Fertilizer Research and 

Education Program, 1220 N Street, 

Sacramento CA 95814 


The Nature of the Nitrate Problem 

In recent decades, environmental monitoring has revealed widespread and steadily increasing amounts of nitrate 
in California's vast underground water resource. The trend is associated with a growing population and with more 
intensive agriculture. Rising nitrate levels in groundwater are known to result from(l) manure generated by 
concentrated animal production; (2) fertilizer applied to crops and landscapes; (3) septic systems and sewage 
treatment plants; and (4) fuel combustion and industrial sources. All of these human activities produce nitrate, 
which is a soluble compound of nitrogen and oxygen. Nitrate also comes from natural sources - sediments and 
rocks, and natural fixation of nitrogen by plants and lightning. Nitrate can move with water down through the 
soil to enter the groundwater supply. 

Although nitrate is a natural com- 
ponent of living systems, too 
much nitrate can cause problems 
- for human health and for the 
environment. One well-known 
potential threat is the relation- 
ship between high nitrate levels 
in drinking water and a rare 
infant disease called methe- 
moglobinemia (blue -baby syn- 
drome). In the stomachs of very 
young babies that have not yet 
developed normal acidity, nitrate 
can change to a related com- 
pound (nitrite) that interferes with 
the blood's oxygen-carrying ca- 



The Nitrogen Cycle 

■ — -i 
- Uoj. , ~ -. 

: *}**'.■■ — * -*.-. 




V^l I 

Adapted from: EPA Nitogen Action Plan, March 1991 draft 

Cancer and birth defects also have 
been the subject of concern in 
relation to high nitrate drinking 
water, but no firm link has been 

The current public health stan- 
dard for acceptable drinking 
water in California is 44.3 milli- 
grams/liter of nitrate (10 milli- 
grams/liter of NO, -N). As shown 
on Map 1, hundreds of wells in 
various areas of the state cur- 
rently exceed this level. 

There also is an economic dimension to the problem. When nitrate in a public water supply reaches or exceeds 
the 44.3 mg/1 standard, costly measures are required. The well may have to be deepened or closed down, a 
different water source may have to be acquired for blending, or expensive water treatment may be required. For 
example, the Orange County Water District has estimated thalwellhead nitrate treatment costs aboutS375 per 
million gallons. In 1986. public water systems in California applied to the State Department of Health Services 
for more than $48 million to correct nitrate violations. The total cost undoubtedly was even larger since many water 
agencies used other sources of funds to address the problem. 

Excess nitrogen can also cause other economic and environmental problems such as oxygen-depleting algae 
growth in rivers and lakes, toxicity to aquatic life, increased calf abortion rates, and even loss of quality in fruit 
and other crops. These are often the 
result of inadequate manure, irriga- 
tion or fertilizer management. 

Additional costs of nitrate in ground- 
water include land use restrictions, 
denial of loans for lack of a suitable 
water supply, and a reduced tax 
base. So the problem of increased 
nitrate levels in California's ground- 
water is both significant and persis- 

Printed with permission from 

the California Department of 

Food and Agriculture's Fertilizer 

Research and Education 

Program,1220 N Street, 

Sacramento CA 95814 



'Note: Each symbol may represent more 
than 1 analysis at same well 

M ap 1: Well Locations where nitrate levels have been recorded at 45 mg/1 or 
greater during the period 1975-1987*) 

CDFA Nitrate Working Group Report 

In 1988, the Director of CDFA appointed a Nitrate Working Group to study the nitrate problem relating to 
agriculture in California. Scientists from the University of California, state agencies and industry participated. 
Meanwhile, the State Water Resources Control Board (SWRCB), in a report to the Legislature, reviewed the state- 
wide problem of nitrate in drinking water and evaluated existing programs. 

The CDFA Nitrate Working Group's 1989 report, "Nitrate and Agriculture in California," also analyzed the problem 
on a state-wide basis. Using a computerized database that includedl2 years of well testing results as well as 
groundwater information compiled by the SWRCB, the scientists reviewed and confirmed locations in the^ate 
where groundwater contains elevated levels of nitrate. 

Their report also: 

. Analyzed the mechanisms of nitrate movement through the soil. Since nitrate moves with water, the best 
way to slow the process is to reduce the amount of water that drains out of the crop root zone, especially 
percolation to groundwater. 

• Reviewed the potential of fertilizer best management practices, the sources of nitrogen and the types of 
fertilizers, as well as application rates and methods. 

• Looked at the problem of animal production in relation to nitrate pollution. Dairies, beeffeedlots and 
poultry ranches are significant sources. Counties with most of these enterprises are San Bernardino and 
Riverside (the Chino area) and Imperial in the south; Merced, Stanislaus, Fresno, Kern and Tulare in the 
San Joaquin Valley; and Sonoma County on the coast. 

The Nitrate Working Group report concluded with five recommendations. Those charges became the mission 
of CDFA's Nitrate Management Program (NMP), which later developed into the Fertilizer Research and Education 
Program (FREP). They are: 

1. To identify nitrate-sensitive areas throughout California. 

2. To prioritize those areas where action is most needed. 

3. To organize voluntary nitrate management programs in high-priority areas in cooperation with local 

governments and agriculture. 

4. To develop nitrate -reducing farming practices tailored to the high-priority areas and that fit into the 

management programs, in cooperation with growers and other government agencies. 

5. To organize and support research and demonstration projects. 

Printed with permission from the California Department of Food and A gri culture's Fertilizer Research and 
Education Program,1220 N Street, Sacramento CA 95814 

Criteria For Nitrate-Sensitive Areas 

The first step in implementing these recommendations was to decide which locations in the state should be given 
highest priority. Two conditions indicate an urgent problem: First, a high level of nitrate contamination in 
groundwater and, second, a population that depends on that water for drinking. 

Those two conditions depend on various factors. University of California soil scientists originally listed five 
criteria for nitrate-sensitivity of an area: 

Groundwater use. Nitrate concentration is critical if groundwater is used for domestic or animal drinking 
supplies. If it is used only for cleaning, cooling or irrigation of most crops, there is less concern. 

Soil type. Sandy or other coarse- 
texturedvoils transmit water down- 
ward more rapidly, and nitrate with it. 
Also, these soils are less likely to 
create conditions in which nitrate turns 
to a gas and escapes from the soil 

Irrigation practices. Inefficient irri- 
gation systems that lead to large vol- 
umes of deep percolation increase the 
leaching of nitrate. Typically, these 
are surface flow systems with long 
irrigation runs. Well-managed sprin- 
kler or drip systems, or surface flow 
systems with short runs, reduce the 
threat of nitrate leaching to ground- 

Type of crop. Crops most likely to 
increase nitrate leaching are those 
that (1) need heavy nitrogen fertiliza- 
tion and frequent irrigation, (2) have 
high economic value, so the cost of 
fertilizer is relatively small compared 
to revenue produced (3) are not 
harmed by excess nitrogen and (4) 
tend to take up a smaller fraction of 
the nitrogen applied. Many vegetable, 
fruit, nut and nursery crops fit these 
criteria, and therefore have more 
potential for nitrate leaching. Those 
with less potential include field crops 
such as alfalfa, wheat and sugar beets. Map 2: Generalized Map of Nitrate Sensitive Areas in California 



All Other Vegetables 
56.4% 517,000 acres 

Lettuce 22.5% 
206.000 acres 

Chart 1: 

Climate. High total rainfall, concentrated heavy rains and mild temperatures lead to more leaching of nitrates. 

Two more criteria for nitrate-sensitivity were developed by FREP: 

Distance from the root zone to groundwater. Less distance means a more immediate problem. 

Potential impact. This depends on such factors as population density and availability of an alternate water 
supply . 

These seven factors — groundwater use, soil and crop type, irrigation practices, climate, distance to groundwater, 
and potential impact-indicate the nitrate-sensitivity of an area. They determined where FREP's initial field 
activities were directed. In general, two regions of the state, the Central Coast valleys and parts of the east side 
of the Central Valley, fit the above criteria/See Mip 2 on prior page) 

The Central Coast valleys are major vegetable pro- 
ducing areas. In this region, irrigated vegetable 
fields are a potential source of groundwater con- 
tamination. The five major crops are lettuce, broc- 
coli, cauliflower, celery and strawberries. These 
crops account for 43.6% of the vegetable acreage in 
California excluding processing tomatoes. (See Chart 
1 and /Appendix 4). 

On the east side of the Central Valley, tree fruits 
and nuts are major crops, including almonds, 
walnuts, peaches and nectarines, plums and prunes, 
and citrus. These crops account for 77.6% of the 
total state fruit acreage. (See Chart 2). Almonds and 
citrus account for 8.2% of the acreage in Califor- 
nia, yet use 12.5% of the total nitrogen fertilizer. 
(See /Appendix 4). 

Fruits and vegetables account for 27.9% of Cali- 
fornia harvested acreage yet use 41% of the total 
agricultural nitrogen fertilizer. 

(The Los Angeles basin and surrounding areas 
where well measurements also indicate a ground- 
water nitrate problem are no longer a significant 
farming region. For that reason, FREP's agricultur- 
ally-oriented program is not very active there.) 

Strawberries 2.2% 
20,000 acres 

CD FA 1990 Stateistical Review 
Figures do not include processing tomates 


Peaches & 

Nectarines 5.9% 

79,800 acres 

All OtherTree 


22.4% 301,100 acres 

Plums & Prunes 
8.9% 119,700 acres 

Citrus 18.69% 
249,000 acres 

Almonds 30.% 
411,000 acres 

CD FA 1990 Stateistical Review 
Figures do not includeprocessing grapes 

Printed with permission from the California 

Department of Food and Agriculture's 

Fertilizer Research and Education 

Program,1220 N Street, Sacramento CA 95814 

Chart 2: 

First Projects 

Using the nitrate sensitivity criteria listed above, three areas were chosen to begin FREP field activities: the Salinas 
Valley in Monterey County, eastern Stanislaus and Merced Counties, and the Fall River Basin in Shasta County. 

In these locations, working closely with growers, local governments, industry, UC Cooperative Extension, the Soil 
Conservation Service and others, FREP is helping to develop improved farming practices. These improved ways ■ 
of fertilizing, irrigating and managing crops are designed to fit local resource and farming conditions and reduce 
nitrate leaching without impairing growers' profits. 

Salinas Valley 

This coastal farming region, which produces more than one-fourth of the nation's fresh vegetable crops, depends 
almost entirely on groundwater-not only for irrigation but also for domestic and industrial water use. About 
150,000 people use Salinas Valley groundwater as a drinking water source. 

According to a 1987 report by the Monterey Water Management Agency, almost one half of the wells sampled 
in unconfined aquifers of the Valley had nitrate levels above th44.3mg/l standard. The report also points out 
that irrigated farms are currently a major source of that nitrate. 

In late 1988, the Salinas Valley Nitrate Advisory Committee (NAC) was established by local authorities to develop 
plans to address the nitrate situation. FREP was invited to participate in this effort and helped implement a number 
of the committee's recommendations. With funds from the State Water Resources Control Board, the Monterey 
County Water Resources Agency, FREP, the lettuce industry, the federal government, UCD and UC Cooperative 
Extension, a number of projects are researching and demonstrating improved farming practices. These improved 
methods are designed not only to reduce nitrate pollution, but to promote more efficient fertilization and irrigation. 
Informing growers about the findings is a built-in part of these projects. (See Appendix 1). 

Printed with permission from the California Department of Food and A gri culture's Fertilizer 
Research and Education Program,! 220 N Street, Sacramento CA 95814 

San Joaquin Valley 

On the eastern side of the San Joaquin Valley, 
particularly in Stanislaus and Merced Counties, many 
farming areas are particularly sensitive to groundwa- 
ter contamination from nitrate. The soils tend to be 
sandy or coarse, with little or no layering to restrict 
downward water flow. The tree crops grown in this 
area require high inputs of nitrogen but their nitro- 
gen uptake efficiency is relatively low. Water deliv- 
ery systems tend to be less efficient, which increases 
deep percolation. Throughout the San Joaquin Val- 
ley, dairying, with its associated problems of manure 
disposal, is a large and important industry. 

FREP is cooperating with a team working on a 
proposed demonstration project on the east side of the 
San Joaquin Valley to help reduce nitrate contribution 
to groundwater from all agricultural sources. The 
cooperative project will include education, technical assistance and cost-share programs for dairymen and growers. 
UC Cooperative Extension and USDA agencies as well as the Regional Water Quality Control Board. Western United 
Dairymen's Association and local governments are participating. FREP also is supporting research to develop strategies 
to reduce potential nitrate leaching in almonds and peaches, and to improve plant nitrogen monitoring techniques 
in orchards. (See Appendix I). 

Fall River Valley 

This small farming region in northeastern California is not high in state-wide agricultural importance but was 
selected for a pilot project because of its small, confined aquifer and its unique combination of rural residences 
in close proximity to agricultural production. The Fall River Valley produces livestock, alfalfa, potatoes, grain and 
specialty crops such as strawberry plants. A recent survey of local wells showed that about 40 percent had nitrate 
levels in excess of 44.3 mgil. 

To address the problem, the Fall River Resource Conservation District is working with a multi-agency team 
including the Regional Water Quality Control Board, UC Cooperative Extension, FREP. local government, and the 
California Department of Water Resources. A project proposal was approved and funded by the State Water 
Resources Control Board in early 1991. In the first phase, about 20 wells throughout the region are being 
monitored. Information is collected not only on nitrate levels but on patterns of land use, population, agriculture 
and geology. Nitrate data will be correlated with proximity of leachfields. type of agriculture, soil type and depth 
of n-ells. The second part of the project is developing best management practices, primarily, for potatoes and 



Soils Need Fertility Maintenance. Soil is a natural 
body of finely divided rocks, minerals and organic 
matter. Sand, silt, clay and organic matter help pro- 
vide tilth, necessary aeration and favorable water in- 
take rates, but they seldom maintain adequate plant 
food to sustain continuous healthy plant growth. 


There are 16 elements that are known to be essen- 
tial for plant growth and development. 

Fertilizers (also called plant food elements) are ma- 
terials produced to supply these elements in a read- 
ily available form for plant use. 




















Three of the sixteen essential elements, carbon, 
hydrogen and oxygen are taken primarily from the 
air and water. Oxygen and hydrogen are obtained by 
plants from water. Carbon and hydrogen are taken 
in by the leaves from the air. The other thirteen el- 
ements utilized by the plant must come from the soil 
or from added fertilizer materials. 

Crop removal of these elements, plus leaching, vol- 
atilization and erosion causes the soil fertility to be 
continually reduced. Turf and landscape plants will 
have poor color (yellow-green to yellow), poor plant 
density-allowing weed invasion and low plant vi- 
gor which increases plants suseptibility to disease 
and insect damage. 

Soil productivity can be maintained by well managed, 
scheduled applications of multiple element fertilizers. 


A fertilizer 16-6-8 analysis adds up to 30% plant food 
Dr thirty pounds per hundred pounds of material. 
What is the other 70%? 

It is not a filler; it is the way the plant food is chem- 
ically compounded so plants can utilize it. 

Plants can't use elemental nitrogen (N), they only take 
up nitrogen when it is in the N0 3 or NH, form. This 
means that for each part of nitrogen you have three 
parts of oxygen with (NOJ or 4 parts of hydrogen 
with (NH,). When nitrogen is in a compound which 
is available to plants, nitrogen is only part of the com- 
pound. The same is true with phosphorus and the 
other elements. Phosphorus is absorbed by plants 
as H 2 P0 4 — , HPO, = or PO,= depending upon 
soil pH. 

If fertilizers were in the elemental form, they would 
be difficult to handle: 

Elemental nitrogen (N) — a colorless inert gas that 
could drift off into the air. 

Elemental phosphorus (P) — catches fire spon- 
taneously when exposed to the air. It is actually 
poisonous to plants in concentrated forms. 

Elemental potassium (K) — placed in contact with 
water it will catch fire, explode and decompose 
into a strong caustic solution. 


A. Primary Plant Food Elements 


Potassium (Potash) 

Plants rapidly utilize these 
elements and unfertilized 

soils normally cannot pro- 
vide them in quantities 
needed for best plant 

Nitrogen (N) 


Promotes rapid vegetative growth (leaf and 
stems) — hastening recovery after mowing 
and imparting vigor to the turf. 

2 A vital element in the formation and function 
of Chlorophyll — the key 'ingredient imparting 
dark green color. 

3 Synthesizes Amino Acids which in turn form 

4. Regulates the uptake of other nutrients. 

5. Basic ingredient of vital compounds - Nucleic 
acid and enzymes. 

Phosphorus (P) 

1. Stimulates early root formation and growth- 
gets plants off to a good start and forms a root 
filter system in the soil to efficiently pick up 

the other available plant nutrients and water, 
improves the strength and stamina of the 

2. Hastens maturity (conversion of starch to 

3. Stimulates blooming and seed development. 

4. Causes energy transformation and conversion 

processes in which sugars are converted to 
hormones, protein and energy to grow new 
leaves and fruit. 

5. Forms nucleic acids (DNA and RNA). 

6. Vital for photosynthesis (greening of plants). 

7. Essential for cell division. 

Potassium (K) 

1. Aids in the development of stems and leaves. 

2. Increases disease resistance and hardiness 
which helps wearability. 

3. Strengthens cell walls, causing grass to stand 
up and reduces lodging. 

4. Affects water intake by plant cells-plants with 
inadequate potassium may wilt in the 
presence of ample moisture. 

5. Acts as a catalyst in Iron uptake. 

6. Essential to the formation and translocation of 
protein, starches, sugar and oil-improving the 
size and quality of fruit, grains and tubers. 

B. Secondary Plant Food Elements 




They are used in somewhat 
less quantities than the pri- 
mary elements, but they are 
just as essential for plant 
growth and quality. 

Calcium (Ca) 

1 . Calcium is an essential part of cell wall struc- 
ture and must be present for the formation of 
new cells. 

2. Deficiency of calcium causes weakened stems 
and premature shedding of blossoms and 

Magnesium (Mg) 

1. Essential for photosynthesis (greening of plant). 

2. Activator for many plant enzymes required in 
growth process. 

Sulfur (S) 

1. A constituent of three amino acids and is 
therefore essential in the formation of protein. 

2. Helps maintain green color in plants. 

3. Improves alkaline soils. 

4. Helps compacted soils-making them loose 
and allowing better water penetration. 

Sulfur Note-There are commonly two types of 
sulfur applied to plants and soils: 
Sulfate Sulfur - SO,; Elemental Sulfur (S) 

Sulfate Sulfur (SO,) 

Sulfate Sulfur (SO,) is the form taken up for 
plant food. Many plants require as much sulfur 
as phosphate in their growth processes. 

Sulfate Sulfur (SO,) is contained in gypsum 
(CaS0 4 ) and other sulfate fertilizers — Ammon- 
ium Sulfate, Ammonium Phosphate Sulfate and 
many turf fertilizers. 

Gypsum (CaS0 4 ) will help reclaim alkali soils 
and make them loose and friable. Alkali soils 
contain sodium which causes soil to disperse, 
puddle and seal up. The free calcium from 
gypsum will replace the sodium on the clay 
particle and allow the sodium to be leached out 
of the soil. 

It also causes the small soil particles to floccu- 
late (join together in small crumbs), leaving space 
between them for air and water movement. 



Too much todium 
attached to clay 
partieltt tendt to 
make the partieltt 
pack together in 
lueh a way that 
water cannot gtt 



Sulfur mattrialt 
furnish tolublt 
calcium, which 
replacer the 
txcttt abtorbtd 

Thi-neoioc » ' WATER 

mrnt q)tow8 
tht roll 
partieltt to 
group thtm- 
ttlvtt 80 
that larger 
port tpaett 
art formed. 

Then when the roil It flooded, the water 
can put through and wath out • xcel8 
Mitt, including todium. 

Elemental Sulfur (S) 

Elemental Sulfur (S) will convert to sulfate sulfur 
in the soil. This reaction can be slow, depending 
upon the sulfur particle size and the soil con- 
ditions. Once it has converted to sulfate sulfur 
(SO,) it is available to the plant. If the soil con- 
tains calcium, it can form gypsum in the soil and 
be used for reclamation of alkaline soils. 

Elemental sulfur will lower the pH of the soil at 
the location of the pellet as it converts to sulfate. 
(See the article on Turf and Sulfur). 

C. Mlcronutrlents: Iron, Zinc and Manganese 

Even though micronutrients are used by plants in very 
small amounts, they are just as essential for plant 
growth as large amounts of primary and secondary 
nutrients. They must be maintained in balance in or- 
der for all nutrients and water to be used efficiently. 

On turf grass there are three micronutrients that are 
particularly important in order to maintain green color 
and plant vigor: 

Iron (Fe) 

Yellowing of grass (Iron Chlorosis) is often due 
to iron deficiency. Iron is required for the forma- 
tion of chlorophyll in the plant cell (causes turf 

to maintain a healthy, green color). It serves as 
a catalyst for biological processes such as res- 
piration, symbiotic fixation of nitrogen andpho- 
tosynt hesis. 

Applications of iron can correct iron deficiency, 
but it may be iemporary in high pH soils, due to 
tie up with calcium. This may require acidifica- 
tion of the soil with elemental sulfur or the use 
of ammonium forms of nitrogen or some other 
acidification agents. As ammonium converts to 
nitrate in the soil, it has an acidifying effect. This 
acidifying effect makes iron and many other el- 
ements more available in high pH soils. 

Zinc (Zn) 

Zinc is an essential component of several plant 
enzymes. It is a part of auxins and controls the 
synthesis of indoleacetic acid which regulates 
growth compounds. Zinc also affects the intake 
and efficient use of water by plants. 

Manganese (Mn) 

Manganese serves as an activator for enzymes 
in plants. Without Manganese, the plants can- 
not use the iron which they have absorbed. It as- 
sists the iron in chlorophyll formation which 
causes yellowish turf to green up. 


"Ag Alert--A Weekly Newspaper on California Agriculture," California Farm 
Bureau Federation. 

Available to Farm Bureau members, this weekly newspaper provides readers with articles 
on current issues in agriculture. Contact your local county Farm Bureau to order this 

Aariculture and Fertilizers , Oluf Chr. Bockman; Norsk Hydro, 1990. 

This book provides readers with different perspectives about fertilizers and fertilizer use 
as well as detailed fertilizer science facts. Contact the California Foundation for Agriculture 
in the Classroom for information on how to order this book; (916) 924-4380. 

Aariculture and the Environment: The 1991 Yearbook of Aariculture. United 
States Department of Agriculture; US. Government Printing Office, 1991. 

This yearbook examines environmental concerns facing agriculture and indicates what the 
United States Department of Agriculture (USDA) is doing to address these concerns. This 
publication is made available by your local congressmen or can be ordered from the US. 
Government Printing Office. 

Agriscience-Fundamentals and Applications, Elmer L. Cooper; Delmar Publishers, Inc., 

This high school agriscience textbook presents general information taught in introductory 
high school agricultural science classes. It is a great reference to have for student research 
and teacher background information. 

Alternative Agriculture, Committee on the Role of Alternative Farming Methods in Modern 
Production Agriculture, National Research Council Board on Agriculture; National Academy 
Press, Washington D.C., 1989. 

This report examines in detail the scientific and economic viability of alternative 
agricultural systems, such as crop rotation and biological pest control, so that many 
challenges facing agriculture today can be overcome. To order this book, call 1-800-624- 

"Bottle Biology," Bottle Biology Program; University of Wisconsin-Madison, Department of 
Plant Pathology, 1630 Linden Drive, Madison, Wl 53706; (608) 263-5645. 

"Bottle Biology" is an inexpensive, motivating way to teach hands-on biology using one and 
two liter plastic bottles. Sign up to be put on their mailing list for newsletters. 

California Farmer, Farm Progress Companies, Inc.. 

This colorful monthly magazine contains articles on current agricultural issues as well as 
editorials, classified ads, weather information and more. Write to P.O. Box 11375, Des 
Moines, IA 50340-I 375 for subscription information. 


California Fertilizer Association's Lending Library of Motion Pictures, 1700 
I Street, Suite 130, Sacramento, CA 95814; (916) 441-1584. 

A variety of videos and slides discussing fertilizer use and water quality are available. 

ChemCom: Chemistry in the Community, Kendall/Hunt Publishing; Dubuque, IA, 

A high school chemistry book that emphasizes hands-on examples. 

"Clear Facts About Clean Water," The Fertilizer Institute; 1990. 

This pamphlet provides detailed information about water contamination, especially ground 
water, drinking water and nitrate contamination, To request a class set of these pamphlets, 
contact Amy Jo Matthews at The Fertilizer Institute, 501 Second Street NE, Washington D.C. 

"Fast Plants," University of Wisconsin-Madison; Department of Plant Pathology-Fast Plants, 
1630 Linden Drive, Madison, Wisconsin 53706; (608) 263-2634. 

Rapid growing plants with many activities are available through this university. Ask to be 
put on their mailing list. "Fast Plants" can be ordered through Carolina Biological Supply at 

"Fertilizer-Perception and Reality" pamphlet, The Fertilizer Institute. 

This pamphlet provides factual information on fertilizers and specifically addresses many of 
the perceptions associated with fertilizer use. For ordering information, write to The 
Fertilizer Institute, 501 Second Street NE, Washington D.C. 20002. 

"Field's Of Gold" Video, California Foundation for Agriculture in the Classroom; 1601 
Exposition Boulevard, Sacramento, CA 95815; (916) 924-4380. 

This 28 minute historical video shows the relationships of agriculture with California history. 

A Glossary of Farm Terms, United States Department of Agriculture; 1983. 

This booklet provides definitions to hundreds of agricultural terms. This is a great 
reference to have available to students during reading or writing assignments. Order from 
Ag in the Classroom, USDA, Rm. 318-A, Administration Building, Washington, D.C. 20250. 

"Improving Plant Production for Human Health and Environmental Quality" 

Handbooks, Potash and Phosphate Institute. 

Five different comic book-type, easy to understand pamphlets provide the reader with 
information on various plant nutrients such as nitrogen, potassium and phosphorus. To 
order these booklets, write to PPI, Suite 410, 2801 Buford Hwy, NE, Atlanta, Georgia 


Livina in the Environment, G. Tyler Miller, Jr.; Wadsworth Publishing Company, 1992. 

This college-level environmental science textbook contains thorough, yet easy to 
understand, information about various factors that affect the environment. It also contains 
many short articles written by key authors that encourage the students to think on all sides 
of issues before making decisions. 

Organic Soil Amendments and Fertilizers , David E. Chaney, et al.; Regents of the 
University of California, Division of Agriculture and Natural Resources, 1992. 

This booklet is a guide to organic materials used to enhance soil quality and promote plant 
growth. To order, write to ANR Publications, University of California, 6701 San Pablo 
Avenue, Oakland, CA 94608-1239 or call (510) 642-2431. 

Science Framework for California Public Schools Kindergarten Throuah Grade 
Twelve , Science Curriculum Framework and Criteria Committee; California Department of 
Education, 1990. 

This document provides suggested guidelines for science education throughout California. All 
science educators should have a copy of the framework available to them. Themes and 
concepts are outlined, as well as guidelines on classroom management and teaching skills. 
Write to the Bureau of Publications, Sales Unit, California Department of Education, P.O. 
Box 271, Sacramento, CA 95802-0271 for ordering information. 

Science Safety Handbook, California Department of Education. 

This document provides the rules, regulations and procedures recommended for using and 
storing particular chemicals in the classroom. Write to the Bureau of Publications, Sales 
Unit, California Department of Education, P.O. Box 2731, Sacramento, CA 95802-0271 for 
ordering information. 

Sunset-New Western Garden Book , Sunset Magazine Editors; Lane Publishing Company, 

This easy-to-use gardening book, written for gardeners of the western United States, 
provides general information on soils, pest control, planting techniques, and fertilizing, 
plus problem solving tips and plant selection guides. Available at most bookstores; this is a 
must for your student and teacher reference library. 

Seeds of Chanae, Herman J. Viola and Carolyn Margolis; Smithsonian Institute Press, 1991. 

This beautifully illustrated book provides an overview of American agriculture in 
commemoration of Columbus' voyage to the New World. 

"Soil Fertility Manual," Potash and Phosphate Institute; 1987. 

This manual, written for farm advisors, provides basic agronomy concepts in an easy to 
understand manner. Soil components, fertilizers, and plant nutrient requirements are some 
of the key points discussed in this booklet. 


Soil Science and Management , Edward J. Plaster; Delmar Publishers Inc., 1985. 

This college-level soil science book provides detailed information on introductory soil 

Western Fertilizer Handbook, Soil Improvement Committee and the California Fertilizer 
Association; The Interstate Printers and Publishers, Inc., 1990. 

This well-organized book provides information on the nutrient requirements of plants and 
nutrient management strategies. Contact the California Fertilizer Association at (916) 
441-1584 for ordering information. This should definitely be part of your reference 
library for use by teachers and students. 



Ag Access 

603 4th Street 
Davis, CA 95616 
(916) 756-7177 

This bookstore specializes in agricultural information. Knowledgeable personnel can help 
you find the resource books you need. Write or call for a free catalog. 

American Chemical Society 

1155 16th Street NW 
Washington DC 20036 
(800) 227-5558 

Request a catalog of materials and programs available for educators and students 

California Association of Resource Conservation Districts 
3830 U Street 
Sacramento, CA 958 17 
(916) 639-6251 

This organization has many soil science activities for all grade levels, including a popular 
comic book titled "Amazing Soil Stories." 

California Fertilizer Association 

1700 I Street, Suite 130 
Sacramento, CA 958 14 
(916) 441-1584 

This association has various videos and pamphlets on general and technical information of 
fertilizer manufacturing, application, safety and more. 

California Foundation for Agriculture in the Classroom 
1601 Exposition Blvd. FB 16 
Sacramento, CA 95815 
(916) 924-4380 

The Foundation has a wealth of materials for educators, including a teacher resource guide 
that provides information on how to order free or low cost classroom materials which 
promote agricultural awareness. Educator workshops and conferences on integrating 
agriculture into the classroom occur several times a year. Be sure to get on the mailing 

Delmar Publishers, Inc. 

2 Computer Drive West, Box 15-015 

Albany, New York 12212-5105 

This company publishes a variety of agriculturally-related science books. 


Discover Science 
20417 Nordoff Street 
Chatsworth, CA 91311 
(818) 341-2535 

This company sells a wide variety of chemicals and lab equipment. 

The Fertilizer Institute 
501 Second Street, NE 
Washington D.C. 20002 

This association has various videos and pamphlets on general and technical information of 
fertilizer manufacturing, application, safety and more. 

Fertilizer Research and Education Program 

California Department of Food and Agriculture 

1220 N Street 

Sacramento, CA 94271-0001 

(916) 653-5340 

Videos and other publications are available on the agronomically safe and environmentally 
sound use of fertilizers. 

4901 W. Lemoyne Street 
Chicago, IL 60661 
(800) 621-4769 

Request a catalog from which you can order a wide variety of classroom materials, including 
chemicals and laboratory equipment. 

17 Colt court 

Ronkonkoma, New York 1 1 779 
(516) 737-I 133 

This company has for purchase a variety of science kits for student use, as well as 
inexpensive "chemtrays." 


1524 Princeton Avenue 
Modesto, CA 95352-3837 
(800) 558-9595 

This company has classroom science and agricultural science educational supplies available 
for purchase. Request their science and/or agricultural sciences catalogs. 

Potash and Phosphate Institute 

Suite 401 

2801 Buford Hwy, NE 

Atlanta, GA 30329 

This organization has colorful, easy to read booklets on potassium, phosphorus, nitrogen and 
other plant nutrients. Write for a list of other materials they have available. 



91 1 Commerce Court 

Buffalo Grove, IL 60089-2362 

FAX (708) 677-0624 

This company sells a wide variety of chemicals, lab equipment and software. 

University of California, Cooperative Extension 

Cooperative extensions provide the public with general and technical information on various 
topics, including agricultural information. The Master Gardeners, Future Farmers of 
America (FFA) and 4-H programs are usually obtainable through this office. A pamphlet on 
current publications available from the U.C. Cooperative Extension is also available. Check 
your local phone book for your county's U.C. Cooperative Extension phone number and 
address (Listed under the name of your county.) 

University of California Sustainable Agricultural Research and Education 

University of California 
Davis, CA 95616 
(916) 752-7556 

This department can answer specific questions you have about sustainable agriculture and 
current farming and gardening practices that are designed to enhance the environment. 

Vernier Software 
2920 SW 89th Street 
Portland, OR 97225 
(503) 297-5317 

Request a catalog to review the various science software programs available. 



Amendment- any material added to soil to make it more productive; usually used for added 
materials other than fertilizers such as lime or gypsum; but a fertilizer is an amendment. 

Anhydrous-- a dry substance; without water. 

Buffer- any substance or mixture of compounds that, added to a solution, is capable of 
neutralizing both acids and bases without changing the original acidity or alkalinity of the 

Chemical elements- a collection of a single kind of atom. 

Conservation- to be cautious and moderate in the use of a resource, resulting in 

Crop rotation- the successive planting of different crops in the same field over a period of 
years to maintain or improve soil quality and reduce pest problems. 

Denitrification- a biochemical reduction of nitrates, ammonia and free nitrogen in soil; 
often done by microorganisms. 

Ecosystem- a system formed by the interaction of a community of organisms with their 

EPA- Environmental Protection Agency; a governmental agency. 

Fertilizer- any substance added to soil or water to increase the nutrients available to plants. 

Fertilizer Analysis- the actual composition of a fertilizer as determined in a chemical 
laboratory using standard methods. 

Gypsum- hydrated calcium sulfate. 

Holding capacity- the amount of water/nutrients that a soil can hold before nutrients begin 
to leach out. 

Hydroponics- to grow plants, without soil, in a water nutrient solution. 

Ion- an electrically charged atom or group of atoms. 

Infiltration- to filter into or through; to move through the soil profile. 

IPM- Integrated Pest Management; a strategy used to reduce pests in a particular location by 
relying first on biological controls, treating pests only when economically necessary and to 
maintain crop yields while avoiding a negative impact on the environment. 

Leaching- downward movement of materials in solution through the soil. If fertilizers leach 
below the plant's roots, the plant cannot absorb the material. Leaching can lead to groundwater 

Legume- normally a plant that has pods whose seeds split into two; often helps with nitrogen 
fixation; examples include beans and alfalfa. 

Macronutrients- nutrients needed by plants in large quantities. 


Manure-- solid animal waste products; can contain some straw of other animal bedding 

Methemoglobinemia-- "Blue Baby Syndrome" caused by high nitrate intake in very young 
mammals which reduces the blood's ability to carry oxygen. 

Micronutrients- nutrients needed by plants in small quantities; usually less than several 
parts per million in a plant., examples include boron, copper and zinc. 

N-P-K-- Nitrogen/Phosphorus/Potassium; the three chemical elements that legally must be 
represented on a bag of fertilizer. 

Nitrate-- the NO3 form of nitrogen that is readily used by plants and is very leachable. 

Nitrification- to break down nitrogen compounds to nitrites and nitrates by bacterial 

Nutrients-- elements needed by plants for proper growth. 

Nitrogen-fixation-- conversion of N2 to forms readily usable for plant growth. 

Periodic Table-- a chart in which the chemical elements are arranged according to their 
atomic numbers; based on atomic weights and chemical characteristics. 

Primary Nutrients- nutrients needed by plants in large amounts; this includes nitrogen, 
phosphorus and potassium. 

ppm (parts per million)-- a very small quantity; equivalent to one drop of water in a 
swimming pool. 

Reduction-- in chemical terms, the gaining of electrons. 

Secondary Nutrients-- nutrients needed by plants in medium quantities. Includes calcium, 
magnesium and sulfur. 

Sustainable Agriculture-- an agricultural system that remains productive, economically 
viable and environmentally sound over a long period of time. 

Tilth-- the act or operation of tilling the land. 

USDA- United States Department of Agriculture. 

Yield-- the amount of product produced on one acre of ground. 



The following chapters and page numbers refer to the 1990 Sc i ence Framework for Ca li forn i a 
Public Schools. 

1 . Chapter 5 A-l, pg. 118 

2. Chapter 5 A-2, pg,120 

3. Chapter 3 B-l, pg. 51 

4. Chapter 4 B-2, pg. 94 

5. Chapter 5 C-4, pg. 142 

6. Chapter 4 B-4, pg. 98